Error 400: access_not_configured - Cannot Install Google add-on

I am trying to install your Google Workspace addon and am getting this message:

Access blocked: Your institution’s admin needs to review [Google Add-on Name]

You can’t access this app until an admin at your institution reviews and configures access for it. If you need access to this app,

Request Access Error 400: access_not_configured

If you are unable to install and Google Workspace add-on, or if the Install button itself is greyed and disabled, you need to contact your domain admin and request them to whitelist the addon.

  1. Open admin.google.com to access your Google Workspace domain admin panel.

  2. Go to Apps > Google Workspace Marketplace Apps > Apps List

Click the Allowlist App button.

  1. Search for the addon name you wish to whitelist in your organization and click the Select button.

  1. Choose Allow users to install this app and click Continue.

  1. You may select Everyone to allowlist the selected addon for an organizational unit or specific groups. To add other groups or organizational units, repeat the steps.