All their reviews are bad on trust pilot; https://www.trustpilot.com/review/upbit.com
Majority of the ratings are 1 star and someone in particular said they requested $15k for them to be able to withdraw. My first advice will be not to put your money there, my second one will be to try any possible way to get the most you can out.

I have not used them and they don't seem to be famous globally. Most of their operations are in S. Korea.