How can I possibly get assigned to 10th Group after Airborne school?

You can’t. You don’t get to choose your follow in assignment and HRC almost never gives you a follow on assignment of your current post unless you’re MACP or a very limited assignment MOS.
But after your next assignment you can possibly reenlist for 10th SFG.

It depends on what you want to do, and why you want to go to 10SFG. 10SFG is an Airborne unit, so you could go over there and then have them send you to ABN School. It would be expected that you go to ABN if assigned to that unit. Going the other way (re-enlisting for the purpose of going to ABN) might get you to school, but after that they Army will put you where they need you most.

If your intent is to get tabbed, then you need to drop a packet for SFAS. But SOF units require enablers, so if that's what you're interested in I'd talk to both HRC and someone in personnel at 10SFG(A). It certainly helps, as others have indicated, to have someone that will vouch for you and to be requested by name for a certain position. On the other hand, a lot of the junior enablers in the various staff sections come right out of AIT. Not everyone agrees with that, but that's how it it works at the moment. You also have Group Support Battalions (GSBs) that are going to have a lot of the enablers that support SOF missions (i.e. UAV operators, chemical decon, etc.) where you might also look at going.

You have to take/pass SFQAS and be selected, a tough row to hoe, and absolutely no guarantees