Do I have to use the app? December 18, 2020 21:18 Updated Yes, the only way to apply and stay on track with payments is by using the Flex app. You can download the Flex app HERE. Related articles Where do I sign up for Flex? What is an online rent portal? What banks does Flex work with? I’m not sure if I completed signing up, how do I know? I am getting an error when I enter my rent portal credentials, what do I do? Comments 0 comments Please sign in to leave a comment.