Go to https://console.developers.google.com and login
Click on Select a project
Click on NEW PROJECT
Spesify Name and click on CREATE
Go to Credentials -> OAuth consent screen
Provide Application name and logo if you want
Provide Authorized domains in this case microsoftonline.com
and click on Save.
Go to Credentials -> Credentials and choose OAuth client ID
Provide Web application as Application type and Name for application.
and for Authorized redirect URIs
Notice that url: sergeydotnetb2c.onmicrosoft.com is url to Azure AD B2C Tenant. To read about how to create an Azure AD B2C Tenant read this blog post.
And now we get our client ID and client secret