How to stop Google Drive from syncing the Mac files?

I had no idea this was happening until recently, but whenever I download anything on my Mac from Chrome—like a PDF or a textbook—it automatically syncs with my Google account. Even photos I take on Photo Booth are taking up storage on my Google account. I’m not sure if I’m supposed to connect my MacBook's files with a Google account, but there must be a way to stop the files from syncing with it. Does anyone know how I can solve this issue?

[Re-Titled by Moderator]