This module is specific to Backdrop. Information on how to install should be provided in the description of the project.
A simple way to use Backdrop's cron to call CiviCRM's cron.
Since CiviCRM 5.x, extension releases compatible with CiviCRM 5.0 are compatible with 5.0 and later. An extension release compatible with 5.25, for example, means that it requires CiviCRM 5.25 or later.