Hi Jess,
Since you want to link your Moodle and Wordpress websites, then you must take a look at our plugins Edwiser Bridge and Single Sign On, you will be able to link you moodle courses with Wordpress using Edwiser Bridge and for a common login credential you can use Single Sign On.
You will have to pay for a new website domian however, Using single sign on a user can login to both websites simultaneously using the same login credentials.
If that is something you are looking for then explore more about Edwiser Bridge here: https://edwiser.org/bridge/