Help... is this a silent killer? HVAC Furnace Installed wrong?? Carbon Monoxide

I recently moved and had a furnace installed. I hired a "legit" company to do the work and after 2 weeks I realized some water dripping from my lightbulb in the kitchen this morning. I went up on the roof and started inspecting and really couldn't figure anything out. After further investigation, I notice the furnace was exhausting into the attic above the kitchen and a lot of condensation had accumulated and that was the cause of the water in the chimney. Yes, I do have 3 Carbon Monoxide detectors ( not cheap ones) but have experimented with some detectors in the past and they let that stuff build up big time before going off). Anyway, after calling the comply on a Saturday, the guy was trying to have me go pick up the supplies from him to vent it out myself. (I live an hour away). And I told him I didn't know enough abbot it and that's why I hired him and paid 2300 bucks for labor. He sent 2 guys out and they ran it out the basement sidewall. I read through the manual for the furnace that can be seen here: -https://www.questargas.com/ForEmployees/qgcOperationsTraining/Furnaces/Lennox_G40UH_X_SERIES.pdf and it doesn't really say you can run it out the side wall and also prohibits venting it without a liner in the chimney (which they didn't do either), so I'm really not sure if this is safe and really starting to think it is not. Model number - G5OUH-48B-090-15