Configure Favorites in Group Policy

I want to configure favorites using group policy; I've got the extensions loaded and have been using them to set a series of 6 browser tabs to open when the end users open Edge.  Its functional, but six tabs loading at startup slows down launch time enough to be a nuisance to the users.

I'd like to slim that down to 1 or 2 tabs at startup but have everything in favorites.  I've discovered the "configure favorites" policy and saw the example they gave and I used that for the six favorites I'd like.  I saved that as a text file \\servername\netconfigurations$\favs.txt; the permissions of that share and file are everyone-->read only, is the file supposed to be a text or an .xml?  The instructions aren't clear.

Thanks!