As per Xbox Support page here
When your Xbox is offline, you can:
- Watch TV
- Sign in to your profile (if you've signed in online before)
- Change console settings (except for profile and family settings; content controls remain in place while offline)
- Play games (provided you've set this as your home Xbox or have a game disc)
- Save game clips and screenshots
- Earn achievements (however, there's limited offline space for game captures and achievements, so you should go online every so often to sync them)
So I'm guessing you will have to set the Xbox as home Xbox.
To change your Home Xbox, go to Settings. Then under the General
Personalization > My home Xbox.
Once you're in the My home Xbox menu you can choose to make the Xbox
you're on your new home Xbox.