(ARCHICAD 23 Installer detected that your operating system is not supported.
For further help with Recommended Operating Systems, please go to GRAPHISOFT Support page.)
So what is your operating system?
Does it match what is mentioned on the support page?
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10