The VBS-HDIP-709P2P Point-to-Point Transmitter requires more power than a typical 3G device, and does not ship with a power supply included.
Each Just Add Power unit requires between 8-10 Watts of power. A 50-watt power supply* will be sufficient to power a single 709P2P and 4 POE Receivers connected inline. Power supply requirements:
Example power supply: https://www.digikey.com/en/products/detail/mean-well-usa-inc/GST60A12-P1J/7703712