Role and mandatory privileges on MongoDB for bi connector

At first I tried to connect by running mongosqld.exe with a user that authenticates with the .X509 authentication mechanism (uses only certs) and has read and write privileges. But it was failing at sampling the schema.

Then I changed to a admin user that was authenticating with SCRAM-SHA-1 mechanism and everything run smoothly.

My question is: Which are the least privileges that a user must have in order to run everything smoothly or if it is possible, only have read privileges for the database?

Thanks in advance!