The demo link goes to a secure https url, but the frzr JS is pointing to the non-secure http url and therefore not loading.
Suggest changing JS src url to just //frzr.js.org/dist/frzr.min.js (to load either, based on current scheme) or https.
Suggest changing JS src url to just //frzr.js.org/dist/frzr.min.js (to load either, based on current scheme) or https.