Change:

my $number_string = 'Your number is \+([0-9]+)';
[download]

to:

my $number_string = 'Your Number is \+([0-9]+)';
[download]

Regular expressions are case-sensitive (Number).

I determined this by removing characters from your regex until it matched. umber is \+([0-9]+) matched, but number is \+([0-9]+) did not. Reducing code is a common debugging technique.