Probably because the M210 Is not compatible with the Pilot app in I pad.
See:
Android
Requires Android 5.0 or above.
Compatible with DJI Crystalsky, Mi Pad 3, Mi Pad 2, Samsung S2, Samsung S3, Huawei M2, Huawei M3, Nexus 9.
Huawei honor 9, Huawei P10, Google Pixel 2. One plus 6, LG G6, OPPO...