File paths. I Think...
When you use the "mpl" option, it exports the MC library data for each file, a bit like so.... (you can open the file in any text editor to see for yourself)
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<MPL Version="2.0" Title="3 random albums not heard in past 120 days" PathSeparator="\">
<Item>
<Field Name="Filename">D:\Music\flac\Bruce Hornsby & The Range\Scenes From The Southside\01 - Look Out Any Window.flac</Field>
<Field Name="Artist">Bruce Hornsby & The Range</Field>
<Field Name="Album">Scenes From The Southside</Field>
<Field Name="Name">Look Out Any Window</Field>
<Field Name="File Type">flac</Field>
<Field Name="Genre">Rock</Field>
<Field Name="Bitrate">882</Field>
<Field Name="Image File">INTERNAL</Field>
<Field Name="Media Type">Audio</Field>
<Field Name="Last Played">1661094500</Field>
<Field Name="Rating">4</Field>
<Field Name="File Size">36256076</Field>
<Field Name="Duration">327.626666699999987</Field>
<Field Name="Number Plays">6</Field>
<Field Name="Track #">1</Field>
<Field Name="Date Created">1446620988</Field>
<Field Name="Date Modified">1647887380</Field>
<Field Name="Date Imported">1446613407</Field>
<Field Name="BPM">107</Field>
<Field Name="Notes">Set</Field>
<Field Name="Lyrics">There's a man working in a field <snip>
When you import an mpl list into MC, it will update/replace/add existing library entries with the data contained in the mpl, and import any files referenced in that mpl, that are not already in the library. If all went well, you should then be able to find the playlist in the MC tree under "Imported Playlists".
My guess is that on export, the files are referenced as found on your Macbook, which are file paths Windows does not interpret, hence, no files found.
I don't know enough about playlists to advise further. Maybe try one of the M3U options. I do not know what the "forward slashes in paths" option is for, but it might be related?