This website can be used to convert magnet links into torrent files that are usable with the current version of Free Download Manager:

http://magnet2torrent.me/

I would suggest that people use this until magnet links are supported directly in Free Download Manager. I have tested and used this with The Pirate Bay, which no longer has torrent files, only magnet links, and that magnet2torrent.me website works perfectly along with Free Download Manager.

Anyway, hopefully soon magnet links will be supported directly in Free Download Manager and this will not be necessary anymore, but for anyone having trouble with magnet links, try using that website along with Free Download Manager, it worked for me at converting magnet links from The Pirate Bay and other torrent sites that have switched to magnet links. Anyone who is having difficulties with magnet links and wants to be able to download them with FDM can use magnet2torrent.me for the time being and it should work, although I really hope they do add magnet link support to FDM so this is no longer necessary.

Oh, and remember to have "Enable DHT" checked in your Free Download Manager settings for BitTorrent if you want this to work.