Can you download direct from the Black pages with out using the download cart?
I know you have probably tried all this by now but just in case bare with me. If one doesn't work move on to the next.
The FTP file access is restricted now so you can't get to see all of the files.
This is a slightly more extreme method.
1. Clear internet temporary files and cookies, then reboot PC. Trainz uses cookies and temp files, could well be a stale cookie or temp file that's causing the problem.
2. Clear Trainz internet Cache. Close Trainz go to Trainz\userdata\cache\internet, delete contents. reboot, then try CM.
3. Clear Stale DNS cache.
Open Command Window, type ipconfig /flushdns > enter. again reboot PC. Stale DNS can cause login problems with sites and other odd things not happening correctly.
4. Reset password in Auran Profile.
Close Trainz, won't work if it's running, edit password and input your same password and save, reboot PC, give it a couple of minutes and then try Content Manager.
5. Reset password in Content Manager.
Again use the same password save, close content manager, reboot PC and then restart.
6. Alternative method if 5 doesn't clear it.
Remove Name and password from content manager, save, close content manager, reboot PC, Start content manager and input original username and password, Save, Close and then restart content Manager.
7. Another trick that sometimes work is to change trainz internet settings from use Internet Explorer Settings to No proxy server, save then change it back and then save again. or if you have it on No proxy then change to IE and back.
Why reboot? So any temporary stuff is hopefully deleted and not hanging around to cause the re-occurance of the same problem.
Obviously not a problem with port21 as WS FTP is working so we can rule that out (Sometimes it's blocked by default in the router and in a very few cases by the ISP).
If none of this works, try using a different DNS server, such as Google's DNS or OpenDNS, I use Open DNS as my ISP' DNS server is not very reliable.
Finally and this worked for me when my FCT packed up, copy the trainz folder to a different location and try running it from there.
I should add that I haven't needed to do any of this for two years now, other than regularly get rid of cookies and temp files. The problem isn't a not having an FCT problem as it can happen with or without one.