There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.
To install Text::sprintfn, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Text::sprintfn
CPAN shell
perl -MCPAN -e shell install Text::sprintfn
For more information on module installation, please visit the detailed CPAN module installation guide.