If your game crashes on startup(PC), do this for a possible fix.

Go to the Windows store, search for Forza6 Apex Demo and start the download on it on the same drive as your Forza 7 install. Let it download for a couple of seconds. Start Forza 7. Stop Forza 6 download. Repeat as necessary whenever you get this crash. If Forza 6 Apex download does not fix your crash on startup issue, try the Forza 7 Demo download as outlined above. One of the two will fix it. Don’t ask me why it works, it just does, however, YMMV, as the user below pointed out.

It worked for you, does not mean it will work for others.
There are so many bugs, this game will not start, and 14 different things “could” fix it, but usually, only one will.
Don’t mistake your own personal experience for that of everyone. But thanks for the tip, another one added to the list of fixes!