I wrote to the support, they answered that I had to fully delete the previous beta, by means of the utility they suggest on the web page, and to reinstall everything. It worked. I do not know who is the admin.
regards
8519 was working in some way in Catalina, 8521 starts with the Licence agreement which overlays the image: no chance to eliminate as well as to access the menus or anything else. I applied the eye tv reporter to clean up everything. no positive result. downgraded to 8519
Bad job, and still an RC. I am a customer not happy from november...