Watch the YouTube Tutorial: https://youtu.be/b8fxx6DqIAw
General Setup
1
Go to Credentials Page
Make sure you are logged in to your Google account and visit the Credentials - APIs & Services page. Make sure to read the terms and conditions and “Agree and Continue”.
2
Create Project
Create a new project by clicking on the “Create Project” button. Fill in the project name, and details and click “Create”.
3
Create OAuth Credentials
Create credentials by clicking on the “Create Credentials” button. Select the “OAuth client ID” option.
4
Configure Consent Screen
Make sure that your consent screen has been configured.
5
Fill in OAuth Details
Create the OAuth client ID. Select “Web application” as the application type and fill in the details.Replace 
{provider} with youtube in the redirect URI.Under “Authorized redirect URIs”, insert your OAuth2 Redirect URI.6
Add Test User
Add yourself as a test user of the application
7
Activate YouTube's API
Go to “Enabled APIs and Services”. Then click on “Enable APIs and Services”. Search “YouTube Data API v3” and activate the API by selecting it and clicking “Enable”. Do the same Process with “YouTube Analytics API” and “YouTube Reporting API”.
Additional Steps for Brand Accounts
When using a Brand account you will need to set your APP to External and setup a test user. You do not need to publish the APP, but it does take time for the changes to propagate. You will also need to add the app to the trusted apps within your google workspace Admin.
1
Go to admin.google.com
Sign in
2
Go to Security Settings
Go to Security → Access and data Controls → API Controls
Click Manage Third Party App Access
3
Configure new App
Click “Configure new App”
Put your Client ID for the app you created in previous steps into the search box and select your app
4
Set scopes and Google Data Access
Set scopes and Google Data Access for the app to Trusted
Once set, click save
5
Wait for propagation
Wait at least 5 hours for the changes to propagate.
After this time you should now be able to add your YouTube channel to your Postiz account