While hiking with a partner can make shuttle logistics easier, provided you both drive your own vehicles, it’s not strictly necessary. You’ll meet plenty of people on the trail and you may end up hiking with them informally for a few days. If you’re looking for a partner to hike the Appalachian Trail with, your best bet is to meet them on local trail club hikes or backpacking trips where you can assess your backpacking partner compatibility in less trying circumstances.