Icon Featured Service: icons don’t appear

Hello,

I’m working on building a website with template “Quality” and I’ve a problem to solve. Under the section “Icon Featured Service” I try to put icons for various services but these are not displayed any way. Can be a problem with the site https://fontawesome.io/icons/ or in my template? I await a good answer and I thank in advance those who will help me.

Cheers,
Jacopo