I want to modify some python or C or whatever files using an IDE on my desktop, then I want to use my laptop to continue the work on the same files but on a updated version without having to download the files myself (like I would have to on google drive for example), just turn on the PC and open the IDE. I've tried Resilio but the free version doesn't allow sync between pc's. How can I do that?
Based on your question, it sounds like you want near-real-time synchronization between the two systems. The best option I've found for this is called Syncthing. It's essentially an equivalent to Resilio, but open source (and therefore free). It's not trivial to set up initially, but once you have it working, it's rock solid in my experience. The one downside is that there's no central location you sync to, so both systems need to be on at the same time to synchronize data between them, although you can work around this by just keeping your desktop on all the time, or getting a cheap VPS to run it on (it works just fine running on the smallest offerings from most cloud hosting providers).