FOR PEOPLE DOWNLOADING THE MODPACK ZIP DIRECTLY FROM THE CURSEFORGE WEBSITE:
Manually downloading modpacks is NOT practical, nor recommended. If you are trying to setup a server, you need to either rent one from Bisect Hosting or use the serverpack to install serverside. You will still need a modded launcher clientside.

Using a modded launcher, such as ATLauncher or the Curseforge Launcher will guarantee a proper installation and make things such as backups and updates much easier.

Unless you are extremely knowledgable, there is no way to use the normal, unmodded Minecraft launcher to install and launch a modpack. Even if you are knowledgeable, a manual installation is a waste of time.