Did you run conduit etc. or does that cable have tough cladding, etc.? How did you connect to breaker box? That seems the trickiest part.
I ordered jacketed 6/3 THHN. No need for conduit unless you are running on top of drywall, which I did not for any length. Wire the breaker box last. Order a 60amp breaker manufactured by the manufacturer of your breaker panel. Torque the 6/3 cables in the breaker box to the breaker manufacturer specs. All done! Don’t forget cable straps for entry points and every 4 feet of the run.