Just install material-icons ttf file then you can insert an icon from the dialog below.
I built keremciu/sketch-iconfont plugin at 2015. Three years ago I put latest version then Sketch API changed and I wasn't able to try it out because of my workload. This new plugin is approaching the same problem with a different solution that's why you only need to install TTF file, no need to import any SVG file anything.
If you'd like to request any font to be added to this plugin, please create an issue here then we can get visibility over which icon-fonts are wanted.