See upstream README file for configuration and usage instruction.
Almost all information from that file is relevant.  However, from
the section "INSTALLATION", only this is relevant:

  * To be performed in place of 'make initdb' from the README's installation
    instructions.

    Initialize the database

      rt-setup-database-4 --action insert --datafile \
         /usr/share/request-tracker4/plugins/RT-Extension-ResetPassword/etc/initialdata

    Only run this the first time you install this module.

    If you run this twice, you may end up with duplicate data in your
    database.

    If you are upgrading this module, check for upgrading instructions
    in case changes need to be made to your database.

  * Edit a file like e.g. /etc/request-tracker4/RT_SiteConfig.d/90-local.pm
    and add the line:

      Plugin('RT::Extension::ResetPassword');

  * Clear your mason cache

      rm -rf /var/cache/request-tracker4/mason_data/obj

  * Restart your webserver

 -- Andrew Ruthven <andrew@etc.gen.nz>  Fri, 02 Feb 2018 03:55:28 +0000