Twoja lista ikon nie zawiera tagu na kuriera, czyli samochód dostawczy, gdzie znajdę więcej ikon niż z tej listy: http://wpsoul.net/icons/

you can find information about icons and about special helper classes of theme in documentation

https://rehubdocs.wpsoul.com/

as you have no actual support, we can't provide any help with this, feel free to study documentation by yourself or update your support if you need customization and setup help. 

<i class="rhicon rhi-fire redbrightcolor mr5">

what is mr5?

to add an icon you do not need to type Mr5 and besides, where can I find all the codes for adding icons? well, how to add an icon color