The gauge power wires should be BEST connected as the schematic suggests directly to a good ground near or on the battery and the +12v wire to a hot when the ignition is on (motor running).
I would configure the 0-5v positive output from the gauge to data log through D10, (ELD, electronic load detection).
The 0-5v ground signal could be connected to D21,D22 but any good ground can be used.
Good luck with your new gauge. These are super useful.
remove resistor r136 and r138 on ecu if using D10 ELD circuit, also you may ground 0-5v analog negative to the same ground as the gauge so long as your Offset on D10 isn't greater then (+/- 0.05 volts) when viewing smanager sensor list voltages. ALSO pro tip unplugging the wideband connector will force the gauge to read 14.7 AFR and push about 2.4 volts out, maybe 2.34 volts. Hondata smanager will translate this into your AFR as 14.7 I would take a voltmeter and meter the output voltage right at the gauge and compare this to smanagers reading and adjust the offset voltage. If you are (+/- 0.05 volts) bring the ground closer to the ecu. Your voltage offset should not be a large number. Anything larger then plus or minus 0.08 volt is borderline too much difference.
Let's not make assumptions, please leave as much detail as possible!