go to this site
then click on "download free"
open the rar and go to—> fontawesome-free-5.0.9\web-fonts-with-css\webfonts
upload on app inventor the 3 ttf (brands, solid, regular)
then you have to select the right kind of ttf, is not like the previous version.
you have to select the correct ttf for the correct icon
i figured out that some icons, if you use the “solid ttf”, is a full icon, if you select the “brand ttf” or “regular ttf”, the same icon is outline
i’m not expert, so i make with “try and mistake”.
let me know