Agree with secondsupra2004, alternator is unrelated. Starter motor isn’t getting power or sufficient power. Open circuit, blown fuse, dead/low battery or bad relay.

Which battery in your picture is the starter battery? The one on the left is pretty old, 2017. Both batteries Known good and charged?

The fuse you blew, is that the 80amp fuses on the ACR or other fuses not shown in the picture?

FWIW, the 2 gauge on the ACR is overkill. Those wires need only to be sized for you max alternator or battery charger charging current. Fuses sized to protect wire size.