The current install button is not supported by any mod manager yet, give it time.
After you download the mod you want, you have the following options:
Basically it creates a
/fmm folder in the Factorio application directory,
after that, you copy the mod packs to
/fmm/ and the individual mods to
The Factorio Mod Manager will let you activate and deactivate mods without having to manually add them or remove them from the folder.
Just copy the mods to
/mods folder in
the Factorio application directory.