Well, as it says, you’re in an unsupported region. There’s nothing that can be done about that. They had pasted not long ago to advise of changes made by Gemini. You can see which regions are supported at NOTICE: New region restrictions on verifying Brave Rewards with Gemini
If you’re not in one of those countries, then linking Brave to Gemini isn’t possible. If Uphold is available you can try using them. Otherwise you’ll just be earning BAT in your browser and unable to turn into cash. You will at least be able to tip content creators if you wish or hold onto BAT in your browser until your region is once again supported