Please be advised that Hungary is not an official supported region for Roku which is why you are unable to add Disney Plus and HBO Max.
Any Roku Player or TV can be activated to any Roku account, however, channel availability/access will vary from region to region. Channels that are currently available in any given region are certified for the Roku devices sold in that region.
The channel is managed and developed by its channel publisher. We suggest you reach out to them to let them know you want their streams on Roku Hungary.