Hi,
Unfortunately, I'm not able to access your link. I'm currently travelling in Japan, and will be for the next few weeks, and your website is blocking access from that country:
"403: Toegang geweigerd
Je land (JP) staat op de zwarte lijst"
Check the settings of your template. It should have a setting for font awesome and make sure it is turned on:
yootheme.com/support/question/172021
When you test again after this, make sure you clean up the template / website cache, and do a hard refresh of the page.