You can register to the UCC here. Please check the official rulebook first:
In the first question, you have to give your Chess.com username.

The second question is the most important. You need to choose your position in UCC for this season. Find more about positions in our rulebook.

In the last two questions, please write your timezone(it will help in the match negotiation) and any suggestions you have for UCC.

Thanks for submiting the form and see you in this season!