HOW TO FIX: I had the same issue since Xcode 26 beta came out. I thought it was a bug and kept trying with each new beta to open and agree from the Downloads folder. Today after failing again to move past the agree button, I decided to move Xcode Beta to the Applications folder.. It worked, I accepted and now I can use Xcode like normal. Usually the system prompts to move an app to the Apps folder but not with Xcode Beta. Hope this helps!