I can see the folder, its directory listing generated by the FM server, and the three files in it and download them all ok.
A link like:
http://fhapgood.fastmail.fm/abstracts/alemi.pdf however will fail, because links need to use the exact names of both folder and file, and (foolishly in my view) you used mixed case names for both. That link would need to be:
http://fhapgood.fastmail.fm/Abstracts/Alemi.pdf