After you Create Subdomain go back to https://console.cloud.google.com
Use the same project that you used for the application of the API
Complete the Oauth Consent steps.
!DO NOT ADD A LOGO!
Do not add a Logo
โ
โKeep this part empty
Add your Domain for example agency.com and for the Developer contact information enter the same email that you are logged in Google Console Cloud
Click on Save and Continue
Click on Save and Continue
Scroll Down and click on Back to the Dasboard
Publish App