With an Oxygen concentrator, you won't need the oxygen regulator. Just hook your hose up to the concentrator (with flashbacks/arrestors of course). It should have a built in regulator of sorts. you will need one on the propane.

Funny note - when you fire it all up to test it out and the concentrator starts beeping at you and saying it isn't making oxygen, crack open the valve on the torch to let the Oxygen flow. I got to that point and thought i had a bad concentrator.