I see a couple things that might not be working here, so let me say that it's really important in Perl to get every keystroke correct, including capitalization.

I use strawberry perl, and to invoke cpan, I simply type

No 'sudo' here. Many treatments show that. To install a module:

There's a lot of SFTP stuff of cpan that is out-of-date. Read what they recommend as newest. Hope this helps