Ok, please try to do following as it seems that the article misses one step:
Store your backup in a safe place to avoid losing it
Create a new website using the same name as your website to move
Then under your new backup location please put your backup file in the directory with the same name as your website (if it does not exist – please create it)
Now you can try to restore backup under your newly created website.
Alternatively: just unpack your backup, rename the output folder to be the same as old folder name on your previous OS and move it to your publii sites directory (you can check this location under Global Settings in Publii) – then restart Publii and it should appear.
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