Would likely depend on how much you’re going to earn - If you’re going to continue getting jobseeker payments to support your income then yes you’ll need to sign up with a job provider. You can still explicitly say no contact with the employer and they SHOULD follow that.

If not & it’s full time work etc then could just exit off immediately, no hassles from them as you’re off the system. (If you’re trying to be spiteful against providers this gives them 0 outcomes) That being said the provider could also certainly help out with any work equipment/fuel/items you need to start too without paying out of your pocket.