I still have a 1st-gen iPad, and I don't really do much with it, but the first two things that come to mind to suggest are:
1) Check what stylus she is trying? Is it an Apple product, or something else?
2) When I go to Settings, I see a section for Apple Pencil, and in that I see a toggle labeled "Only Draw with Apple Pencil." If that's on, try turning it off.