Server denied POP3 access for the given username and password. Server returned error: "Authentication failed" on Gmail

Server denied POP3 access for the given username and password. Server returned error: "Authentication failed" on Gmail

Trying to add Zoho email to Gmail to receive messages and I get this error:
Server denied POP3 access for the given username and password.
Server returned error: "Authentication failed"
I see other support tickets for the same issue but they are very old and not applicable now e.g. one suggests enabling POP which doesn't seem to be an option now. Another suggests disabling 2FA which doesn't seem to be an option now. 

Please help. How can I add the email to Gmail? It can send email via Gmail, but it can't receive email.