Everyone is getting that error message I believe. The app will still run, you just lose the "access control"function, which simply allows you to individually allow or ban devices from your wifi network.
Ahh OK that makes more sense. Here's a bunch of D1 kernels. I'm pretty sure they all support tethering. Since you're doing it for your pal I'd keep it low just in case their phone doesn't want to play nice with a particular choice.