Freerider is developed by a single person (me) and I am willing to help as much as I can. My knowledge in regards to Mac and Linux is very limited though since I don't own either a Mac or Linux machine myself. There's a quite large and helpful hobbyist community out there though, but it can be tricky to get hold of the right person. The official Freerider thread at RCgroups can be worth a try if you're a member there.
The OSStatus error 99999 seems to be a not too uncommon problem, and not specific to Freerider:
https://github.com/JohnCoates/Aerial/issues/469
http://hints.macworld.com/article.php?story=20130803041717457