Is there a way to make it so people have to pass the post test before that can move on to the next module?

Hello,

Yes this can be done by creating a custom end of Module screen. The end of Module screen appears after every test. In this screen you would not allow the user to move forward until they passed. This would be done by setting the "continue to next module" button as hidden. Then applying an action to show it when the system variable of current module score is greater than or equal to the current module passing score. (Or you could just set the later manually too.)

Working with master pages and custom end screens