Create a studio account
BGA Studio uses separate accounts from Board Game Arena, so you need to create a Studio account even if you already have a BGA account. You can use the same name for your Studio account.
You can find the account creation form on the homepage of https://studio.boardgamearena.com/.
Follow the steps to confirm your account. This actually creates ten accounts, from YourNickname0 to YourNickname9. For now, just use the main one, YourNickname0.
Next, learn how projects and the framework work before creating your first project.