"Skins Folder Missing" message appears on Serum.
Serum is not able to find your presets folder. It might due to a few reasons and the folder might have been relocated.
If you know where your presets folder is located, then point to it (On windows, the folder is in Documents\Xfer by default)
If you don't know where your presets folder is located, the easiest thing is to reinstall the FULL version of Serum and restart your DAW. At this point, Serum should work and you can decide to relocate the folder and point Serum to the new location of your choosing.
Note: some older versions of Serum had a bug when the presets folder was installed in a path with unicode characters, for instance if the computer's user name was in Japanese, Arabic, Hebrew or any languages not using ASCII characters. If you encounter this issue, please update Serum or move the presets folder to a path without unicode characters.