If not, you can force a re-download of the mod by looking into C:\Program Files (x86)\Steam\userdata\\ugc for files & folders referencing the mod (for instance 203770_subscriptions.vdf and \referenced\45371260977302539\mod\), deleting them and restarting Steam client. Verify mod file and archive are present in folder ~\Documents\Paradox Interactive\Crusader Kings II\mod.Note that Steam cloud sync appears to be broken for mods with capitals in user_dir. Make sure you have Steam Cloud enabled.In case no download progress appears in Mod tab, check the setting for downloading while game is running ( Steam -> Settings -> Downloads -> Allow downloads during gameplay).Try subscribing to the mod in Steam client, while CK2 launcher is already started.