You will not be able to add a new user until the required field validation has passed
At this point, you can use whether to continue or to add another user. The default is not to add another user after adding the first user.
If you would like to add another user straight after the current user, slide the switch to "Add Another User" and a fresh dialogue will appear once you have clicked "Add":
You have now successfully added a user.
If successful, you should see a Success notification, or you will be informed of any issues.