Your service account will have an email as identifier
2
Attach the Google Drive API to the service account
On the service account created, on the menu "API", add Google Drive API into the created service account.
3
Download the google service account json file
On the service account page, go to "keys" tab.
Click on "Add a key" and select JSON.
You will have the possibility to download the json file now.
4
Attach the service account to a google drive folder
On Google Drive, add your service account (reader only) on the google drive folder you want to index. You can find easily your service account by his email identifier (step 1).
5
(OPTIONAL) To index only a subfolder of your Google Drive
In the case you only want to index a subfolder of your google drive (let's imagine you use this service account for multiple applications and for KAI you only want to index a sub folder). Note down the name of the folder.
Final output :
service_acount: upload the service account json file downloaded on step 3
folder_name: if you want to only index a specified folder, fill it with the folder name retrieved on step 5, else let it blank