Cant i play shared xbox one games (xbox anywhere) with my pc?

No, you need to be signed in on Windows 10 with the account that bought the game, which in this case is not the same one as you simply use to play on Xbox One. Sharing games with Home Xbox only affects playing on the console, it does not allow an account
that did not purchase the game to play on Windows 10.

I hope this clarifies the situation.

Xbox cloud content would be shared with the PC if you're playing an
Xbox Play Anywhere game.

Fallout 4 is unfortunately not one of these titles, so your Xbox saves are not transferrable to the PC version of FO4 (or vice versa).

As the others said, only Play Anywhere titles will share savegames between Xbox and PC versions of the game.

For example Gears of War or Forza games on the PC share the savegames with the Xbox Version. For a complete list check https://www.xbox.com/games/xbox-play-anywhere

Games that exist both on PC and Xbox and are NOT on that list do not keep your Xbox and PC savegames in sync.

Hello Jim,

In this reply, I hope that the explanation given will clear things up and further assist with the issue being experienced.

Games can be shared with multiple accounts on both PC and Xbox One.

This will depend on if the title is an Xbox Play Anywhere title. On a Windows PC, if the account that owns a specific game on the Xbox Play
Anywhere list installs a game onto the PC, another account will be granted access to then install it from the Microsoft store.

On an Xbox One console, the home console has to be manually changed from one to another, and is limited in some sense.

These would be the ways to share Xbox entitlements with various other accounts.

Best wishes!

Only downloadable content that you buy for an Xbox Play Anywhere
game that you own will also be playable on both
Xbox One and Windows 10
PC. If the game is not part of Xbox Play Anywhere you can't share it on PC.