Hi Jan,
you can check the status of the installed DEXT driver in terminal.
Open a terminal window
Type: systemextensionsctl list | grep promise
Outcome should read [activated enabled] for driver 21.1.0
If not, check the driver extensions in your Mac's system settings:
General > Login and Extensions > Driver Extensions > click the 'i' symbol on the right.
Here you can enable the Pegasus DEXT driver installer if necessary.