

Another install question
Sick or changing batteries in my old thermostat and the local energy savings program was 'selling' Nest Thermostats for $5 so I got there but already pulling my hair out installing the first one. Confirmed with the HVAC guy who just installed a new oil furnace that we already have the wires needed for it (see photo of old setup). And after connecting it all I'm getting a message on the home app that it's not seeing the common wire. Can someone tell me what I've done wrong or if the HVAC guy is wrong?
TLDR: idiot homeowner trying to install and needs help
Thanks in advance.