If 1500 indicates 1.500 the installer is definitely too old to hold the music.
I received a mail myself but bought the expansion again on Steam (where it is definitely installed, but does
not seem to make its way into the game's in-game playlist), so I didn't try the attached installer.
I will check the file name when I get home from work, though.
The least I can confirm for now is that the new music actually exists and indeed turned out quite nice
...
EDIT:
I still got a copy of the mail on my phone: The link (and attached file) is called 2000 (not 1500), so you likely got the wrong mail there...
Any chance you received another one? If not you might want to check your (and your email provider's) spam filter...