It's very likely you are missing the 24V wire required to power the thermostat electronics. I would recommend an Ecobee smart thermostat with the power extender kit. I had to go this route and it works perfect and you should be able to do it yourself (if you aren't comfortable just purchase the equipment and have an HVAC person install and maybe service your furnace if this hasn't been done for some time). Canadian company as well so always nice to support home grown products. If you get the premium model you can ditch the old humidistat (I see in your photo) as the Ecobee will do a better job controlling humidity in your house. See link below.
https://support.ecobee.com/s/article...-Kit-no-C-wire