Hey izymc,
I just published an update, v2.6.4, which brings batch transcription and updated underlying libraries.
Try it now and see if it works!
Here are the devices that can run the latest macOS
https://support.apple.com/en-us/122867
Also worth noting that PrivateTranscriberPro only will work with the M series macs. Intel based macs won't work.
Basically it should work with all M1/M2/M3/M4/M5 based macs, which means you need to have a Mac from at most 2020 (mac mini M1 is the oldest one to be supported)