1. Create a service account, making use of the optional step of linking it to your project

2. Add a key to the service account
  => browser downloads a JSON file of the credentials generated

3. Access the Enabled API page, and enable (add in) the Cloud Google Vision API

[ You might also like to add in the Google Maps API]

4. Back in the Google Project area, create a key

5. Add in the enabled API(s)

[You might also like to restrict it to your web domain]


For Recaptcha, need to sign up
  https://www.google.com/recaptcha/admin/site/345787649
  v2, (I am not a robot)


Also consider activating:

  Maps Javascript API

  Google Authenticaion -- OAuth 2.0 Client IDs
  

6. Now transfer/copy the service account credentials JSON file to your
   Greenstone3 installation to:

  <GSDL3SRCHOME/web/etc/gs-service-account-credentials-key.json