I believe they are referring to the fact that the file and login need to match.
The game doesn't force you to capitalize any of your user when you login. For example, I can login as:
Phloxenfree
phloxenfree
PhlOxEnFrEE
etc.
The game allows this, but if you export a preset as Phloxenfree_1.fhp, then I need to login specifically matching that, as Phloxenfree.