You can add your bank account to your Gemini account by:
Going to the Funding Sources page and under Automatically link bank click on Get Started
Continue through the flow to enter your bank login credentials via Plaid
If you are unable to link your bank account via Plaid or prefer not using your online banking credentials to register your bank account, please exit the screen and navigate to Manually link bank and input your wire information. Once your bank account information is set up, you can complete the bank verification process with a successful wire deposit into your account.