How may I simplify the registration process I Try to use RNG to allow student user to registrer for company interviews (the events). I set up a View on my event to allow student to register for an interview. 

It seems a bit complex because they had to click on a link (register) to a page where they have to click on a create button under a select Identity where there is only one mandatory "My account" radio ?

Is there a better way to do that with RNG, or maybe a more suitable module, I am indeed trying to create a n,n relationship between user and event.

I give a try to basicCart module, but I don't need the order part.
You could do it using Flag and Views. 

Once you create a node flag, then all the user needs to do is click on the node flag to register to the event/interview. 

If you need to know which users have registered for an event, in Views, simply add a relationship of flag (can't remember the exact relationship name, but I am sure you can figure it out, might be "users who flagged").