Andy,
A few other things you can try. This seems to be an issue with something about your Mac configuration, rather than something on Graphisoft's end, even though weirdness with Macs is rare. On the other hand, since 16 did install for you... it's got to be frustrating!
First and easiest is to create another administrative user account, log out and log in as that new admin user and try again. Must be an administrator.
If that doesn't work, restart your Mac in Safe Mode, then restart normally and try again. Often Safe Mode clears out some lint.
Pushing the permissions repair to the extreme - download the free Onyx and after it performs the disk checks, let it do all of the defaults under 'Automation' to run maintenance scripts / system cleanup / permissions repair again. Reboot; try installing again.
I suspect a permissions problem, like Nick. Was your Macbook Pro a completely new installation - or did you migrate your user account and apps from another Mac? Did you change your user account name at any point?
Have you pulled up Console after the installer quits (assuming none of the above are successful)? Any log messages at the end of the "All Messages" view that give a hint for why things stopped?
Karl
PS Also, assuming above that you've run Software Update and your Mac is 100% up to date.
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB