AFAIK MEP uses whatever font are installed on your machine. Downloading a font file will bring it to your hard drive but not necessarily place and index it under Windows font manager. Installation may vary with version of Windows as it involves folders not normally available (for writing) to all users. Here's a screen shot after right clicking on a recently downloaded font file
The install option shows my anti-virus icon which apparently takes care of privilege issues. After installation, the new font 'AC Mountain' is available to MEP -- and all other programs.