Hi again,
just unpacking it and putting it in the /saves folder should work.
Have you checked that you haven't accidentally introduced an extra folder layer or something?
What you put in /saves should be a folder, with the name of the world (unless it was renamed), and in that a bunch of folders named "advancements","data","DIM1" etc and a couple of files like "level.dat".
That is the same /saves that contains the new world isn't it?
If you can't get it to work you could try uploading the backup somewhere and post the link so we could test it but it's unlikely to be corrupted.
And you seem to know the difference between Java and Bedrock so I doubt you'd be trying to load a Java save in the Win-10 version or vice versa.
Have you tried just copying the whole /saves folder from the other PC?
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