I am having the same problems on iPhone. I emailed them and they were quick to reply:
thanks for your request. Unfortunately we got some trouble with incorrect logins.
We already fixed this bug, but the update will be uploaded to the appstore next week.
We have a little workaround - in the meantime you can try to put your phone into flight mode, start AppJobber, enter the valid login, put your phone in normal mode and then submit you login.