The cloud environment and your local environment have different databases. Data table entries that you commit locally are not committed to the model and moved to the cloud with your code. In order to log into the cloud app, you will need to log in as the MxAdmin user and create new accounts.
Based on your comment, it sounds like you already know how to log in as MxAdmin in the cloud and can get to the create new user screen. When there, you see the user roles for Administrator and User. Check the following things: Make sure that you have actually deployed the latest commit. Simply committing is not enough to get the code to the cloud node, you need to create the deployment package and then move that package to the correct cloud node. This process is outlined in our Mendix Administration learning path here:
Also, can you confirm that you have made User Roles and not just Module Roles? If you say it works locally, I suspect you have done this correctly. More information on the distinction between user roles and module roles are here: