You will need to create a new Service Account and obtain a private key associated with the Service Account. The key is downloaded as a JSON file upon creation of the Service Account.
Click on the gear icon, to the right of the agent name.
Under the GOOGLE PROJECT section, click on the name of the Service Account.
This will take you to the Google Cloud Platform Service Accounts page, but you first need to update the Service Account's role.
Click on the menu button in the upper left hand corner and click on IAM & admin.
Click on Service Accounts in the left hand menu.
Click on the Create Service Account button at the top of the page.
In the pop up, enter a name for the service account.
Click on Role. Under the Dialogflow category, select the desired role.
Dialogflow API Admin
Full API access
Dialogflow API Client
Session level API access
Dialogflow API Reader
Read-only API access
Check the Furnish a new private key option and make sure JSON is selected for Key type.
Click the Create button.
Download of the JSON file will start. Choose a location to save it and confirm.
Once complete, you'll see a pop up with a confirmation message. Click Close
Turn the bot on Set the language you want to use Upload the JSON file Enter your project ID Enter your Private Key Enter the email address you use to login to Dialgogueflow Test and save.