it is real pity that your hoster dont give the PHP-Parser the php-zip function for scripting use. (must be compile to the php-parser)
oxwall use this for all things how update/install etc.
Please make a phpinfo.php an look if is really not insert
the "gzip" function is for the compression of the HTTP-Transfer between server to client and not for the compression/decompression of files on the webspace.
greets
FaceT