That’s what other person tried to tell you, it’s no longer supported for Brave. The official notice is at NOTICE: New region restrictions on verifying Brave Rewards with Gemini
Only the countries listed can connect Brave to Gemini. Croatia is not one of the listed countries, therefore it means you won’t be able to connect and is why it told you that your region is not supported at this time.
It is supported in that you can see ads and earn BAT. You can even tip content creators. You just won’t be able to have that BAT sent over to Gemini or anything until they decide to allow your region again.