If you’re going to be using the PhotoDay Capture app on more than one device, you'll need to invite each user separately. You can add users by clicking on Settings in the upper righthand corner of your Studio Panel - and then Users in the lefthand navigation.
If you're adding photographers from your PhotoDay Home via mobile web, navigate to your settings, then My Studio. From there, select Studio Information, and then Users. You will then be able to invite users to use the PhotoDay Capture app!
Note: Avoid sharing logins across user devices as this can affect how data syncs with the gallery.