You’ve been banned or suspended even though you only just registered – or perhaps you’ve been on the site a while and you’ve been banned for copyright infringement or similar.
See video for an explanation of why this might be, and then email firstname.lastname@example.org AND go here to log a request: https://help.redbubble.com/hc/en-us/requests/new?ticket_form_id=16465
I should clarify that by ‘non-English speaking countries’, I specifically mean “non-Western” countries. RB does seem to allow people from Germany, Spain, etc. It tends to be places like India, Rajasthan, Algeria, Morocco that result in suspension (just a few recent examples from the FB group).