Assuming you're talking about ActivePerl, PPM has been phased out, and will not be available if you have 5.28 or later:

NOTE: PPM is being phased out as ActiveState moves forward with a new and improved solution for Perl package management across all platforms. While PPM has been included in all versions of ActivePerl up to and including version 5.26, the number of modules with which it worked has steadily declined. As a result, starting with ActivePerl 5.28, PPM modules are no longer available.

From http://docs.activestate.com/activeperl/5.24/perl/faq/ActivePerl-faq2.html

See also https://www.activestate.com/blog/goodbye-ppm-hello-state-tool/ for more information.

And PPM has AFAIK never been recommended with Strawberry Perl.