Credentials
For the credentials, you will need the following:1
The Project ID
2
The Service Account Private Key JSON

How to get the Project ID
1
Go to your Google Cloud Console’s projects list.
2
Choose the Project ID of the project where your Cloud Storage is in.

How to get the Service Account Private Key JSON
1
If you don’t have a service account yet, create a service account following Google’s Documentation.
2
Then follow the steps in Google’s Documentation on how to create a private key in JSON format. See sample below showing how a private key in JSON format looks like.

Configuring the Service Account
1
Go to the Cloud Storage in your Google Cloud Console
2
Click on your desired Bucket
3
Then click on Permissions and click on Grant Access
4
Input the Service Account under New Principals
5
In the Role field, search for the roles Storage Legacy Bucket Owner and Storage Legacy Object Owner and select that. Then click on the Save button.
Complete Block Credentials
1
Input the Project ID for your project found in the previous steps.
2
Then copy the whole contents in the JSON file created in the previous steps into the Service Account Private Key JSON field and then click on Validate.