Updated 01/25/2025
If you don't have one, you'll need to setup a Google Project to get your Client ID and Secret. Create a project here
It will make you create a billing account, but using your project for only OAuth is free.
Then create your OAuth client here
Authorized redirect URIshttps://yourportainersite.com| Application type | Web application | 
| Name | Portainer | 
| Authorized JavaScript origins | https://yourportainersite.com |