I try to explain.
At first, you need to create VM in Parallels using VHD with 21354 build.
Then, you need to go to uupdump.net. Use browser into your VM (running download scripts from Windows is more easy task).
Click "dev channel"
Select arm64 21390 build:
View attachment 17995
Then you can choose language, and other options. Suppose, you want standard us-en edition, so click "Next".
You'll see the following page:
View attachment 17996
Click "create download package".
You'll get a .zip file inside you download folder. Extract the archive. There will be the script "uup_dowload_windows.cmd" inside. Run this cmd file. (Windows will warn you but allow script to run)
When the execution of the CMD will be finished you'll get .iso file with arm64 21390 build.
Double click .iso file. Windows will mount iso as a new drive. Run Setup from this drive. Standard Windows upgrade will start. When upgrade will be finished you will have 21390 build into your VM. Enjoy
You can delete the folder with script and all downloaded files afterwards.
Click to expand...