Under project info, you can find your project id. Save it as you will need to use it later in the process (make sure this is the correct project where your Datastore DB is located).
In the search bar enter IAM & ADMIN and click on it from the drop-down menu.
On the left side pane, click on Service Accounts
In the upper panel click on create service account
In the new screen, enter the service account name. You could use "Rivery Datastore". For the description, you could use "Used for extracting data from Datastore via Rivery" then click on create.
In the search bar, search for cloud datastore and select the Cloud Datastore User, which allows for read and write access to the Datastore. Then click on continue.
Click on the Create key button
In the screen opened to your left, choose p12, and click the create button.
A p12 key will be downloaded to your computer, make sure to save it as you would use it in the next steps.
Click on Done
The new service account will appear in your service account screen. You can recognize it by the name and description you have previously given it. Copy the Email of that service account, that is the service account email you will need to enter in the next steps.
Define the connection in Rivery
To set the connection all you need is the Service account email and the p12 file you created in the previous steps and project id.