I found what I believe to be an error in the following document.
https://www.mongodb.com/docs/ops-manager/current/tutorial/install-simple-test-deployment/

In the section "5. Create the Ops Manager Application Database directory," it instructs to execute the following command
sudo chown -R mongod:mongod /data

In my environment, the mongod user does not exist and I get an error, but looking at the passwd file, the mongodb user and mongodb group seem to exist. The version is 11.7.

I think the correct command is as follows
sudo chown -R mongodb:mongodb /data