Turn the vacuum on and let the magic unfold as it sucks out the clog. When done, switch off the shop vac and check to see it worked, and if needed, repeat the process.
It’s best to switch back and forth with the exhaust and the suction modes to bolster your vac's drain unclogging force. This will effectively mimic the force of a plunger.
Ensure that your vacuum is a "wet/dry" type and not a "dry only." If you attempt a wet pickup with the latter, you could be electrocuted and risk damaging the equipment.