I found the problem.
It downloaded ok for me with QMP, but not with the extension....
That message means that cell A1 of the first sheet does not contain either "Profile Name" or "Preferences", but looking at the cell, it looks like it is OK.
When I replaced the text with freshly typed "Profile Name" it then downloaded OK, so going back to the original version I found the cell contained "Profile Name ", not "Profile Name". An extra space character got appended to the end of the cell and the comparison code is not stripping off any extra characters before making the comparison.
That will go into the bug list for the next plugin update.