If disabled the options at left as shown in the above screenshot, you don’t require to log in for booking the trips. Enabling this option requires a Customer login before booking. Enabling this option will enable the registration on My Account page. “My Account page” is by default created b the plugin itself.
If you disable both of this option then you will get the link in your email that will lead you to the page from where you need to enter the username, password and email.
If you enable both of this option then you will automatically get the username and password in your email so you just need to enter email only while creating the new account.