Create a Folder in a Team's Shared WorkSpace

It sounds like you have the right idea here, but note that the 1-7 numbers in the guide you're referring to are just examples; you shouldn't actually be using those real calls.

Using the ID of the "Shared Workspace" as you mentioned (apparently starting with "84..." in your case) as the "root" in the "Dropbox-API-Path-Root" header is the right way to write in the team space though. And you would put the "Scanned Docs" path component in 'path' variable, along with the name of the new folder you want to create.

So, to summarize, your call should look like this:

curl -X "POST" https://api.dropboxapi.com/2/files/create_folder_v2 \
    --header "Authorization: Bearer <ACCESS_TOKEN>" \
    --header "Dropbox-API-Select-Admin: dbmid:..." \
    --header 'Dropbox-API-Path-Root: {".tag": "root", "root": "84..."}' \
    --header "Content-Type: application/json" \
    --data "{\"path\": \"/Scanned Docs/NEW_FOLDER_NAME\",\"autorename\": false}"

It sounds like you've already tried that though, and still got an error, or created the folder in the team member folder instead. I recommend double checking that you've copied the right ID though, as the IDs for different areas in the same account can look similar, e.g., may both start with "84..." in your case.

If this still isn't working for you, we'll be happy to take a closer like, but we'd need to see the actual values you're sending. In that case, please open a ticket with the code you're using, including the actual values (but please redact your access token) so we can check on that for you.