I'm trying to power a 100 amp sub-panel and have a spool of "CAROLPRENE (R) WELDING CABLE - 600 VOLT - 4 GA " wire and was wondering if I can use this to reach my goal?

No, notice the marking on the cable states "Welding Cable".

First off, a "subpanel" must be fed by a wire fully rated 100 amps, either a #3 copper or a #2 aluminum.

Second, welding cable is considered as cord, and cannot be used as permanent wiring method.

#2 SER aluminum cable is very popular for what you need. Some areas require conduit, best to check with local codes to see what is allowed.

I believe welding cable is considered "flexible" and as such is not permitted "as a substitute for the fixed wiring of a structure" NEC 400-8. The AWG may be the same but UL approval would not be the same.