The best thing to do is to do physical, on-the-ground outreach. Part of the success of Tinder as well as many other apps before it were that they threw great parties and events on or near college campuses. The promise of free booze, free food, or really free anything will draw a crowd. Start in your own backyard and then recruit "college ambassadors" and pay them a small flat fee to host the parties and provide them a small incentive structure to hit a certain number of registered attendees.

Happy to talk through this with you as I've had some success with college and high school outreach initiatives in the past.