It's either your upload or the host you are using.
The download size is 185 bytes, that's far too small. .FMF files are around 42 KB. Can you upload to another host?
Thanks
Sadly it looks like you are out of luck. All the tactics posted here are .tac and FM18 on OSX only accepts .fmf files. I can browse all my FM15, 16 and 17 tactics, but any downloaded from here don't work.