Create OAUTH2 consent and Client ID. Click 2.
Select CONFIGURE CONSENT.
On next screen add a Name and your email id in two places. SAVE and CONTINUE.
On Scopes, click SAVE and CONTINUE.
On Test Users, click SAVE and CONTINUE.
On Summary, click BACK TO DASHBOARD.
Click PUBLISH APP
Next Create Credentials and select OAuth client ID
Give it a Name and select Web Application as the Application Type.
Go to the Authorized redirect URIs section and add URI. The URI you need is on the clipboard!
Copy Client ID and Client Secret to the clipboard and SAVE.
Paste the items in the Homey App screen.
For 2.0.0 skip next part to 2.0.0 onwards
Click the Enable SDM and enable PUBSUB API button and select the enable button.
The app now shows the Authorize button, click it and you will be asked to allow access to the needed resources. The app is marked as unsave as it is not verified by Google. So just select advanced settings to continue. DO NOT USE BACK TO SAFETY, the app will not function if you do so.
From app 2.0.0 onwards:
Click the Enable Resource Manager API and the Enable Resource Manager API buttons.