The proper way to handle this is to create the project using the Google API Console and authorize all the APIs needed for this project.
Afterwards, you will have to select the APIs needed by following the steps from this article here.
In order to retrieve the credentials for the project, you will have to select the project you created and based on the type of application you plan on developing, you will have to select the type of credentials needed.
Selecting APIs & Service
Selecting Credentials
Then based on your choice, you will end up retrieving the credentials and use them in your application.
Reference
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