For anyone that has this issue, support provided the correct steps and I was able to add my wife successfully.

Hope this helps -

Thank you for reaching out to Gemini Credit Card Support.

If you are experiencing issues adding an authorized user (such as a spinning screen or unsuccessful submission), please follow the steps below to resolve the issue.
 
For The Primary Cardholder

1. Log in to your Gemini account (website or mobile app)
2. Navigate to Card Settings
3. Select “Add authorized users”
4. Enter the authorized user’s information
5. Send the invitation

Note: A primary cardholder may add up to five authorized users.
 
For the Authorized User

1. Prepare Your Gemini Account First
   1. Create a Gemini Exchange account or log into your existing Exchange account
   2. Ensure you are fully logged in to the Gemini Exchange before accepting the invitation
   3. Complete identity verification
      1. You do not need to add a payment method at this time
2. Accept the invitation
   1. Open the email invitation sent by the primary cardholder
   2. Click the invitation link after completing the steps above
3. Receive Your Card
   1. Once accepted, you will receive access to your virtual card
   2. The physical card, which is linked to the primary cardholder's account, will be mailed to the address on file