Error 404, Requested entity was not found

Hello,

i have created Service account in Google Cloud,
Added that account into my website’s Google Search Console in users as admin,
Created Key in json and added into Instant indexing Plugin,
Activated Instant Indexing Api from Google Cloud for that same service account.

at the end, i am getting error: Error 404 – Requested entity was not found

Please help.

The page I need help with: [log in to see the link]