Open the Google Play Console and login to your account.
Select Settings tab (cog symbol), followed by the API access tab and then click the Create Service Account button on the bottom of the page (if the button is not shown, you need to click „Enable API access“ first):
3. Follow the Google Cloud Platform link in the dialog:
4. Make sure that you're logged in with the same user as on the Play Store Console and then make sure the Google Play Android Developer project is selected:
5. Click the Create Service account button at the top of the developer's console screen:
6. Provide a name and a description for the service account to recognize it later.
7. Click Create
8. Click Add user role and search for "Service Account User", select it.
9. On the next screen, click Create key, select JSON and download the file.
Email it to us.
10. Close the current browser tab.
You will be back on the Google Play developer console.
11. Back on the Google Play developer console, click Done to close the dialog
12. Click on Grant Access for the newly added service account:
13. Go to the tab "Account permissions" and leave the defaults set. (make sure at least all rights for Releases and Store Presence are ticked:
14. Click Add user to close the dialog.
15. Now, go to Users and permissions in the main menu. Click Invite new users
16. Enter email@example.com as Email address and grant either "Admin" Account permissions (easiest), or at least all permissions in the sections for "Releases" and "Store presence".
When we have received the email with the JSON key and the invitation for the deployment user, we can start deploying the app for you.