Once you are admitted to the University, you are sent an an email from info@admissions.acu.edu titled "Ready to be a Wildcat? Complete your housing registration." This email contains your ACU ID (Also called your Banner ID), which you will need for this process.
Navigate to https://www6.acu.edu/newaccount/
Enter your ACU Username (e.g. abc12d) or Banner ID (e.g. 000123456). The system will tell you whichever you did not enter. From there you will also be prompted to set your password.
The first time you log in after setting your password, you will be prompted to set up security information for future password resets. You can find information on that process in this support article.