I just recently downloaded a file that adds the map builder to my game, and the English Update from Caesar Heaven (?) And after installing them, the game loads normally but when I launch it it keeps asking me to insert the Disc. This game is a digital download that I bought off of Amazon though, so I never had a disc from the beginning. Does anyone know if it's a specific file that made my game think it needed a disc? If I can't fix it I'll probably just uninstall/install again, I was just hoping someone might be able to help me first.

Why would you try to install a patch that you already have? Now that the executable has been replaced with one that is meant for the retail version, you now have to verify the game data or reinstall it.

Are you sure you downloaded this file for the editor? You most likely installed the 1.0.1.0 patch instead, which replaced the c3.exe with a version that asks for the CD.
Your best course of action is to reinstall C3 from the digital download, and then add the editor files from the link.