You got me to look up how these meters work. Fascinating. I see there are no moving parts, and they say you can blow out a system right through the meter, plus it is waterproof enough to be installed underground.
I see two details that are probably relevant to you.
First, in the FAQ, they say this:
I have a reclaimed and/or grey water sourced irrigation system with no backflow preventer. Can I still use the Wireless Flow Meter?
Definitely! Reclaimed and/or grey water sourced irrigation systems do not need backflow preventers with the Wireless Flow Meter as the source is not potable drinking water. Simply follow these instructions, and ensure there is at least six inches of straight pipe between the water source and the Wireless Flow Meter.
Second, in the advanced installation instructions, they say this:
Pump included in the irrigation system WARNING Pumps may cause erroneous flow readings due to excessive vibration on the pipe. Install the flow meter as far from the pump as possible.
If you choose to install a Wireless Flow Meter on a system with a pump, a minimum distance of 10 ft is between flow meter and pump is suggested. Install at your own risk.