I am still unable to install Beta 4. I get the classic "Download Failed" message after starting the update. However, by visiting https://developer.apple.com/download/release/ in Safari on the DTK, I have been able to click "Download" next to macOS Big Sur, then Click Install via the App Store that pops up, and then Click Agree. I now have BigSur installed successfully on the DTK :-)

I think we have the same problem... I have the Apple Developer Transition Kit (Apple/Arm Silicon) with macOS Big Sur 11.0 Beta (20A5299w) and I am unable to get Xcode to work at all. I tried to install Xcode, but it hung during the "Installing Components" phase when I first opened it. I then forcefully restarted the computer and now when I open Xcode I see the message Loading a plug-in failed. with the text: The plug-in or one of its prerequisite plug-ins may be missing or damaged and may need to be reinstalled.. Opening it via the Terminal.app shows: /Applications/Xcode-beta.app/Contents/MacOS/Xcode ; exit; 2020-09-20 12:46:51.273 Xcode[637:9847] [MT] DVTPlugInLoading: Failed to load code for plug-in com.apple.dt.IDE.IDEiOSSupportCore (/Applications/Xcode-beta.app/Contents/PlugIns/IDEiOSSupportCore.ideplugin), error = Error Domain=NSCocoaErrorDomain Code=3587 "dlopen_preflight(/Applications/Xcode-beta.app/Contents/PlugIns/IDEiOSSupportCore.ideplugin/Contents/MacOS/IDEiOSSupportCore): Library not loaded: /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice   Referenced from: /Applications/Xcode-beta.app/Contents/PlugIns/IDEiOSSupportCore.ideplugin/Contents/MacOS/IDEiOSSupportCore   Reason: no suitable image found.  Did find: /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice: mach-o, but wrong architecture /Library/Apple/System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice: mach-o, but wrong architecture" UserInfo={NSLocalizedFailureReason=The bundle is damaged or missing necessary resources., NSLocalizedRecoverySuggestion=Try reinstalling the bundle., NSFilePath=/Applications/Xcode-beta.app/Contents/PlugIns/IDEiOSSupportCore.ideplugin/Contents/MacOS/IDEiOSSupportCore, NSDebugDescription=dlopen_preflight(/Applications/Xcode-beta.app/Contents/PlugIns/IDEiOSSupportCore.ideplugin/Contents/MacOS/IDEiOSSupportCore): Library not loaded: /System/Library/PrivateFrameworks/MobileDevice.framework/Versions/A/MobileDevice   Referenced from: /Applications/Xcode-beta.app/Contents/PlugIns/IDEiOSSupportCore.ideplugin/Contents/MacOS/IDEiOSSupportCore ... Reinstalling Xcode makes no difference, likewise I downloaded Xcode 12.2-beta and tried to run it, but I receive the same error. How can I get Xcode working on my Developer Transition Kit?