If you have 2-factor authentication enabled, you need to create an application password as per support.google.com/accounts/answer/185833?hl=en. and use that generated password in the application. As username you should use the full email address (like: firstname.lastname@example.org).
If you do not have any additional security in place (only user and password), you simply can use your username and password in the application. I however strongly suggest to enable 2-factor as per Google's instruction.
There is no difference in the free and pro version for accessing Google accounts.