It seems that you need to pass ScoreHand() an array of your hand. The following worked for me (assuming the correct score of your sample hand is 6405):

my $userinput = <STDIN>;
#As,Qc,Td,6c,3h
chomp $userinput;
my @hand = split /,/, $userinput;
my $score = ScoreHand(@hand);
say $score;
#6405
[download]

edit: you can also pass it what the module refers to as a ShortHand. This seems to be a string containing all the cards in your hand, but appears to give errors very easily.