They don't give much info do they? My guess is it's some sort of consumer paper.
If you're just starting out it pays to have known good paper. Why chase your tail anymore then you have to? If you want cheap to get started on watch Ebay for somebody selling roll paper. Make sure it was well stored. Or even buy yourself a fresh roll of 8" or 10" wide paper. Assuming you're making 8x10s. By the time you've finished a roll you'll have learned the paper and the process. A 275 foot roll of 8" paper is about 330 8x10s less waste. A similar roll of 10" would be 400+ 8x10s.
BTW you're just starting out by printing other peoples photos? You're a better person then me-) I grabbed about 15 of my negatives that had all been taken at the same time on the same roll of film and that caused me enough trouble when I started. I can't imagine how much hassle doing other peoples must be.
RA-4 is supposed to be RA-4. Maybe others can comment I've only used a private label kit from Fotochem and Fuji chemicals. Mostly with Kodak paper.