Problem with Keynote and HDPC protection

I am a university professor and have been using my macbook pro 16" INTEL for several years for teaching. All my slides are in Keynote.

Recently all the lecture rooms have been equipped with a CYNAP system.

Well I can't use my mac any more for projecting slides. The tech claims is a mac problem due to HDPC protection. The classrooms only have HDMI and I have tried 2-3 different USB-C to HDMI adapters, but the result is always no projection.

Is there any workaround?

It seems to me absolutely crazy that macs cannot be used for projecting Keynote slides via HDMI in classes