Do me a favor. If possible, record the sound so I can hear it and confirm it is the belt.
Since everything is new, something is placing a heavy drag on the belt if it is making noise. Or, it is improperly installed or loose (which wouldn't make sense), or something is getting on it.
What I would suggest is this. If it is the belt, I would remove the serpentine belt and spin all belt-driven accessories to see if there is one that is hard to turn. Also, make sure the belt is properly aligned on all pulleys and there is nothing such as engine coolant or oil getting on the new belt. Additionally, confirm the belt is properly routed.
I attached the directions for belt removal and replacement below. Try this and let me know what you find.
One last question. Each time the alternator was replaced, was it bad and replaced with the same brand alternator?
Let me know.
See pics below.
Images (Click to enlarge)
Saturday, May 29th, 2021 AT 7:47 PM