RE: Dynamics Marketing Custom Font
Hey Mario and all,
I realize, that this topic has been inactive for some time, but given no accepted answer has been posted, please find my full summary on Dynamics 365 Marketing and Fonts here: fordosa90.medium.com/dynamics-365-marketing-fonts-the-complete-guide-f3df6082710f
As for your actual question, am I correct to assume, you have uploaded your font as WebResource into Dynamics itself? So under advanced settings, customize system (or within a solution)? Your link looks like that. For a custom font to be used, it needs to be publicly available - easiest way to test is checking in a private browser. WebResources of Dynamics (Dataverse) are behind password.
In addition, depending on where do you store the font itself (Azure, Wordpress, Web server, SiteCore, PowerPages, Portals, ...), you might need to set CORS settings too. All this you can check in the above blog post.
Be mindful, that additional limitations apply - such as using custom fonts in Emails - please check the blog post for further details.