Check that these are all true:
The user exists as a mobile user in the account. Click Mobile Users on the left menu and verify the user has been added. Note the email address which is the ID of the mobile user.
The mobile user has logged in correctly using the same email address. Make sure the user has not accepted the default credentials (email@example.com) but has entered his own email and password.
The form has been uploaded for the platform the user is logging in on. If the Android checkbox is unmarked during upload, for example, Android users will not see the form.
The form has been deployed to the mobile user, or to a group the user belongs to. A form must be uploaded, published and deployed before a user will see it. Click Applications on the left menu. If your form is already uploaded, click on its name to reach its deployment page. There you can publish it if it's not published, un-hide current deployments to see who it's deployed to, and deploy to anyone else you choose. If the form has been deployed to a group, click Mobile User Groups on the left menu to make sure the user belongs to that group.
The account has not exceeded its subscribed number of devices. If your account has too many devices registered, you can remedy this by choosing Mobile Devices on the left menu and selecting devices to unregister. Tip: If you select all devices and unregister them, each active device will re-register as people log back on.
The mobile user's device is connected. If the device is not connected to the Internet the user will still be able to log in and work with forms, but new forms will not become visible in the list and cannot be downloaded. If the user is having trouble connecting, try closing the Formotus app and starting it again.