Many of them do. Most don't require you to pay anything to become a partner, although they usually want some assurance that you are going to take their partnering programs seriously. Usually that requires you to be able to send them some sort of registration document showing you can legally conduct business activities (i.e. acting as a sales representative) where you live.
In the U.S. that usually means you need a Tax Certificate - which goes by various names since these are issued by the individual State taxation authorities. In my home state of Connecticut, we use something called a Sales & Use Tax Resale Certificate
As far as recommendations, I'd suggest you Google "remote backup" and have a look around for what might work best for you based on where you live and what they're offering.
Get copies of partnership agreements and read them carefully. Be very wary of any business opportunity that claims to "sell itself" as the saying goes. Nothing ever does. If it did, they wouldn't be needing to recruit you. And be forewarned, selling something is always a lot harder than it looks.
The only partner programs you should even consider are those that just pay a straight commission on what you sell.
Be wary of any commission schedules that have sales quotas. Usually these offer you minuscule commissions until you reach a certain sales volume. The reason the less legitimate companies do this is because they know your first sales calls are going to be to your friends and family. Those will be the easiest sales you will ever make. After that, things will get considerably harder and most people will give up. Industry statistics indicate that about 90% of the people who enter sales programs will drop out after the first year. The dodgy companies know that, so they take advantage of it by paying you as little as possible while you are hitting all the people you know for business. Basically they are exploiting you for your personal connections.
If a company offers you free training or sales materials, that's a point in their favor. But be sure to avoid anything that requires you to pay
for something as a condition of getting into the program. That is almost always the mark of a "get rich quick" scam.
I'd also strongly suggest you get some legal advice before you sign anything.
To be successful in sales will require (like everything) an investment of time and effort on your part - time and effort that might be better spent in furthering your education at this stage in your life. So think things through before you make your move.
And that's my hastily written tuppence!