Despite not being cross-buy, the game does support functionality between the Xbox console and the Microsoft Store/Xbox App version for PC.

Your progress, achievements, and Gamerscore sync via the cloud as long as you use the same Microsoft account.

Today, the Xbox console version and the Windows PC version are treated as separate purchases . 💾 Cross-Save & Progress

The "cross-buy" buzz originally came from a 2016 pre-order promotion where digital Xbox One buyers received a free Windows 10 code.

Quantum Break is a standard Xbox Play Anywhere title. This means buying it once on the Xbox Store does not automatically grant you the PC version (and vice versa) under normal circumstances.