I got a skyfactory 3 server and downloaded the forge version, but when I start it comes a list of mods or whatever that is, it always says FML mod: '' in front of it how can I play
You don't have to download Forge you have to download the whole modpack. You get that in the Curse Launcher.
Hello should I download the server pack or the normal one? And where should I put that in? In the mods folder?
It's easiest if you use the Curse Launcher. There you can select the modpack and simply install it.
https://curseforge.overwolf.com/
You can of course also download it from the site and copy it into your vanilla installation. For this you need the normal pack, not the server files.