The region where I live in Turkey is not among the options, but I can choose it as a citizenship
how i am sign up to uphold
You can’t.
Not sure what you’re talking about. Main thing is if you check https://support.uphold.com/hc/en-us/articles/360026786712-Non-Supported-Geographies- you’ll see that Uphold says that no new accounts can be created in Turkey.
If you check https://support.brave.com/hc/en-us/articles/6539887971469 you’d see Brave shows that only people with existing accounts can link to Rewards. Well, in particular they listed Turkey as Türkiye *
and then explained: * Uphold no longer offering new accounts in regions marked with *
why just only people with existing account can link to reward
Because Uphold isn’t letting you create accounts. You have to ask them why. Nobody here can tell you. Often it’s either because of laws/regulations or it’s because of fraud. But again, that’s Uphold’s policy and decision. Nobody here from Brave can have an answer. There’s nothing else to say.