Crusader is a combat routine for Gladiators and Paladins and is written on the ACR platform.
Upon purchase and installation, Crusader will show appear in your ACR window if your in-game job is a Gladiator or a Paladin. If you are unfamiliar with the ACR platform please follow this link. Features
Below is a screenshot of the ACR window with Esper as the selected profile.
If you need support or if you have a question I can be reached through e-mail or through Discord (messaging software).