Thank you for your reply.
I've already taken a look at these files. There are three different .lib files (amino, aminont and aminoct), and I don't know which one I should choose. I've read that they're related to glycoproteins, so I got even more confused. And in these files I couldn't find a .frcmod file, unless it has a different extension... Any ideia?
I haven't used MDWeb, but you can find lib files in the download on the parameters page:
Note tgz and zip are just two different compressed files. Pick one you can open and I guess go with regular GLYCAM when using AMBER-99SB, not the EP version.