Distinguish fees that may be payable to anyone else for any part of your work - eg if you used a sample and have to pay for it - from the money raised by your work.
If you owe someone royalties for Rupie's use of your work with the sample in it - you pay it not him.
The other side of it is you getting the royalties for your own work.
How to explain "non-exclusive"? Hmm. You write a song. Copyright arises automatically (even in the USA, since the USA joined the Berne Convention). Only you can authorise anyone to do any of the acts restricted by copyright. That's exclusive. It excludes everyone else, unless you permit what they do.
A non-exclusive right, someone else can permit things, as well as you. So if you give Rupie a non-exclusive right (for example) to authorise downloads of your music, either you or he can authorise that thing. So if you get offered a paid-for contract for downloads of your music, if you are prepared to accept 1 cent per download, but Rupie is prepared to accept 0.5 cents, he gets the contract and you get nothing.
If you get offered a songwriting contract or a music publising deal (invariably only ever offered on an exclusive basis) you can't give the exclusive rights to the songs you put on mysapce 'cos Rupie already has concurrent non-exclusive rights with you.