With your GCP project created, you’re ready to add a service account.

From the project page for your GCP project, click the menu button in the upper left, and hover over the “APIs & Services” section. Then click “Credentials.”

On the next page, click “Create credentials” and select “Service account”. Then, enter the name of your service account and an optional description that will help you remember what it is for:

Click “Create.” The screen will move to the next step, where you are asked to set the service account permissions. If you want to support the built-in reading history feature of Library (optional) you should select “Cloud Datastore User” as the role. Otherwise, you can leave this blank:

Click “Continue.” Before selecting “Done”, create a key for your service account by clicking “Create Key”:

A panel will open on the right side of the screen. Leave the default (JSON) selected and hit the “Create” button.

Save the JSON file the page downloads in a secure place, such as a password manager like LastPass, for future reference. You’ll need it when setting up your Library instance.

Finally, you will need to give the service account email access to your shared folder, if applicable. Navigate from the "APIs & Services" menu to the "IAM & admin" menu in the console and select "Service accounts."

Here, there will be a list of service accounts associated with your project. Copy the service account email from the page. Go to your shared folder in Google Drive, select "Share" from the dropdown menu, and paste the service account email into the input box. This email should have a format similar to {service-account-name}@{gcp-project-name}.iam.gserviceaccount.com.

Note: Unclick the "Notify people" box in the lower right corner of the popup window to avoid getting a Delivery status failure notification email from Google.

Once your service account is created, continue setting up Library by enabling and configuring API services.