Service Account type of connection can be used for Google Big Query and Google Cloud storage. The process is the same for both connectors.
To create an authorization you need to upload a service account file (resp. Key) in JSON format. To generate and upload the JSON Key follow these steps:
ON GOOGLE INTERFACE
1) In the Google Cloud admin section / Big Query open your service accounts
2) Select your project or create a new one
3) Click 'Create service account' once the project is selected
4) Click 'Create Key' and choose Key Type JSON
GOOGLE BIG QUERY REQUIRED PERMISSIONS
When authorizing Datatap with Big Query we require the following permissions:
1) Upload JSON key generated by Google Cloud / Big Query to the connection
Find further information here under 'Creating service account keys'