These guidelines are current as of Archicad 25.
You can install Archicad from the disk image on the shared drive. It's also available from Graphisoft directly. We keep copies of Archicad installers going back, well, back far enough that not all of them will run on our current platforms. They are located at 3 Resources/AC/AC Program Files/[versionNumber].
For a given version of Archicad, there will be a current un-updated dmg with a build number in the file name. There may also be a dmg that has 'Update' in the file name. If so, install the update after the main installation. (We try to keep only the most current update in this folder.)
Archicad build numbers are four digits, and they increment in the first digit. So you may see 3000-something, 4000-something, 5000-something, etc. If you see more than one dmg with the same build level, use the highest numbered dmg.
(A word on disk images because they are still weird after all these years. A disk image (extension: .dmg, often called a dmg) is file which, when opened, mounts a volume in the local filesystem just as if you had inserted a physical disk. It will appear in the Finder sidebar, and will probably open a window. Some applications are drag-installable, and to install the application you just drag it from that window to your Applications folder. Sometimes they even provide an alias to your Applications folder to make the process clearer. Once you have installed the application, you can/should eject the imaginary disk.)
Archicad is not drag-installable, so you need to run the installer. When the dmg window opens you will see an icon named "Archicad 25 Installer". Double-click that.
Follow the directions. I don't customize the installation. Use the default location, /Applications/Graphisoft. I don't import Work Environment settings; as far as I can tell this has never worked properly. (Maybe it works now. Fool me 4-6 times, shame on me.) Yes on the Dock icon, yes on checking for updates, but not preview updates.
Full Disk Access: For new installations, you need to give Archicad 'Full Disk Access', which is done at System Preferences --> Security & Privacy. When you update, the installer will prompt you to do this again, but it is not necessary.
New version installations usually require a restart. Restart if it asks you, but you need not restart immediately. If you need to apply updates to the version you are installing, you can do so right away without restarting first or even running the original version. Run the main installer, run the most recent update, then restart just once.
There are a couple things that are beyond the scope of the installer.
Goodies
Goodies, which term is just awful, are quasi-non-supported add-ons available from Graphisoft. Even though they don't support them. Three of them are core functions which for some reason Graphisoft likes to pretend aren't core: Accessories, Check Duplicates, and Polygon Count.
The goodies used to be separate downloads, but now they share one installer (at least in the USA version), where you can select which ones to install. The goodies installer is a dmg located on the server next to main Archicad installer. Run it and choose the goodies name-checked above.
Goodies only need to be installed the first time for a new version. After that, they are handled automatically by any future update.
Work Environment
Our Work Environment is heavily modified, and to me the default Archicad environment is profoundly disorienting and I can't do anything with it at all. So right after the first launch I import the work environment. The work environment is stored in the preferences, so if you are re-installing a version you have used in the past, the work environment might be OK at first launch.
DXF-DWG Translators
We currently do not use custom translators. The default translators meet our needs, and if they need to be tweaked we will tweak them. The templates should default to "03 For as is output" and "02 For editable import".
Archicad Updates
Since you wisely opted to let Archicad check for updates during installation, it will do just that periodically (weekly, or change it in Work Environment). It used to notify you when an update was available.
That was too easy, and not programmer-brain enough, so now the update availability notification is buried in Action Center, where you will see a red dot on the Update tile. It falls to you to check here periodically.
The update could be for the application or the Archicad library or both. Go ahead and do it; they usually fix more things than they break. The updates will wind up in your downloads folder. (Alternately, you can get the updater from the 3 Resources location above, unless I haven't noticed it yet, thanks to Action Center.) The files are disk images once again, and the update process is very similar to the original installation. It knows what to update and usually doesn't require a restart.
If Archicad is acting up in any way, the first thing to check is that you are using the current version.
If you are installing a version that has an update, remember to install the goodies before the update.
If you are installing a version that has had several updates, you only need to install the most recent one; it includes all the previous fixes. We keep the most recent update dmg on the server next to the main installer.
The only caveat for updating immediately is if you are working in Teamwork. In that case, all users in a project have to update together, along with the BIM Server application which is running the project.