Hi Oddbjorn,
Pegasus 2 R8 does not work on Mac Studio M2 Utility.
You should not use anything from the Pegasus2 downloads page with the exception of the firmware file if a firmware update is needed. The Utility was written for an ancient macOS, possibly High Sierra and it probably won't work on Tahoe.
For a Pegasus2, this is the Promise Utility from the Pegasus32 downloads page that you should use.
Also, be advised that with the Studio Max, the front USB-C ports are not Thunderbolt and you will need to use the USB-C ports at the back of the Studio Max. All ports in the Studio Ultra are Thunderbolt.