Reach360 sharing vs enrollment

What is the difference between sharing a rise 360 course with a person,  by using the link or QR code vs enrolling the person?

example. With self registration turned on, I can share a course to a person, once they click on the link If they have an account the lye will be taken right to the course. If they do not, then clicking on the link will result in them being asked to create an account, after which they can run the course, I have done this successfully.

however a person who registers in this fashion does not show up in the list of learners assigned to the course, nor does the course show up in their list of courses. They do however show up in the global list of users, and when one views the activity for the course they do show up there too. 

The problem I am trying to solve is in our system users will register for training using say CVENT, I then need to automatically assign them to the course. The two step process of having to verify if they have an account and then assigning them to the course seems not to be possible in Zapier. Sharing seemed to solve this beautifully save for the fact that once the link is in the wild you’re screwed, and it has the above problems. Any ideas on how to do this ?

thank you in advance