I would upload all Lua files to the server and have content downloaded by WorkshopDL as it is faster, and from my experience, mounts better than FastDL does. I only use FastDL for files that should not be uploaded to the workshop or for some content that you get with downloaded addons (such as from GModStore) including fonts. A common misconception is that the 'fast' in 'FastDL' means it's faster than WorkshopDL, when it doesn't have anything to do with the speed you download it necessarily.