The file um5.5.2.tar.Z is a compressed tar file containing the Umoria 5.5.2 distribution. To transfer it, set the FTP to binary mode (type "binary"), get the file, and then type "zcat um5.5.2.tar.Z | tar xf -" to unpack the file. If you already have Umoria 5.5.1, you can get the file patch551-552.Z, which is in the patches directory. Uncompress it, and apply it as a patch.