Hi, John. If you're looking for the route in the "Collection" screen, third-party routes do not show up there. You need to go to the Main Menu, select "Single Player", then choose the scenrio type, either Standard, Career, or Free Roam. That should solve your issue. Routes can be made to appear in the Collection screen but it's more effort than many route creators wish to put into their routes. Some do, most don't.
Please let me know if this gives you what you need.
Best,
Marc
