Hi Guenther,
thank you for your question. Yes, REXYGEN 2.50.9 was tested with Raspbian Buster without any error. Just follow our Getting Started Guide (https://www.rexygen.com/doc/ENGLISH/MANUALS/RexygenGettingStarted_RasPi/RexygenGettingStarted_RasPi_ENG.html).
If you encounter any difficulties, let me know. I will be happy to help.
Regards, Tomas