Pay attention to the error icons
Sometimes when uploading an icon set, you may see an icon displayed next to the icon set’s name.
If you mouse over this icon, it will tell you exactly what the problem is.
Click the image to enlarge.
If the plugin is telling you that you’re missing a stylesheet, make sure you upload a stylesheet with a name identical to the font files you uploaded.
Likewise, if the plugin is telling you that you’re missing font files, make sure you upload font files with names identical to the stylesheet you uploaded.
The most common mistake people make when uploading an icon set is not naming all of the files in the icon set the same name.
All files in the icon set must have identical names.
If your font files are all named:
then your stylesheet for this icon set must be named my-awesome-icon-set.css