I didn't really have to worry about humidity, I live in PA it's always humid here. I would lift the lid a little and pour a smidge of water on day 20/21, if you need humidity fast, put a damp paper towel inside, it will raise it quickly. I've never used a humidity measurer.
37.5 degrees for temp, I didn't have to add much water as we have really high humidity. I only put a little bit on the bottom so it could evaporate faster. If you put too much in it won't create the humidity if you need it higher.
Super simple, set it to 37.5 degrees - arrange the eggs in the turner, if it's dry where you are, put a little bit of water in and keep an eye on it. At lockdown, take the eggs out, remove the second layer, put a rubber shelf liner on the bottom mesh layer, arrange the eggs back in the Bator...