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#11
You have 20H2. Therefore you need a 20H2 iso file. If you use the MS media creation tool that will give you 21H1, so if you wish to stay with 20H2, use the other options e.g. Heidoc iso downloader in the tutorial on downloading an iso file.
Then (short form once again):
Rt click iso file, click Mount (available by default).
Open new drive letter created in f. explorer
Double click setup.exe