You seem to be confusing modules filters and path filters, and ignoring all of the posting/formatting advice given.

FProt::Client is a module, not a CPAN path (it's in ~avar/), examples of the differences are explained in the CPAN::Mini documentation.

If you simply don't want to get any module containing the word 'FProt' in its name try:

#!/usr/bin/perl

use strict;
use warnings;

use CPAN::Mini;

CPAN::Mini->update_mirror(
   remote => "http://your.chosen.mirror/",
   local  => "/local/path/here",
   trace  => 1,
   module_filters => [ qr/fprot/i ]
);
[download]

Or simply alter the filter accordingly to suit your needs.

See also Writeup Formatting Tips.