As long as you’ve linked your Xbox One account to your Epic Games account, any purchased content and progression you’ve acquired is accessible across Xbox, PC, Mac, and Mobile.
Since you are already playing on Xbox One, you will need to register full account details before accessing the progress on PC and Mac. In order to register full account details login with your Xbox Live credentials following the steps below:
- Access the Official Fortnite Website
- If you are already logged in, hover over your display name and select “Sign Out”
- Hover over the silhouette next to “Download” and select “Xbox”
- Sign in with your XBL credentials
- Register full account details to associated with the Epic Games account linked with the XBL
* When registering account details you will need to use an email address that is not already registered with another Epic Games account