Anyone else having issues with this box constantly becoming unresponsive? Also I have user.txt but user own wont let me claim it? What’s the deal?

There is a thread for this box immediately next to the one you created - you might get a better response there: Official Blunder Discussion - Machines - Hack The Box :: Forums

Its also worth adding any extra detail you have about the response when you try to claim it because there are a few reasons why this might be the case.

Chances are good that the box was resetting at the time which expires the flags.