AiCam uses iCloud for data exchange and authentication. The streaming device and the viewing device must use the same iCloud account for this to work. The iCloud service may take some time to sync the data.
If you have a device which uses a different iCloud account, you can add it as a guest device. To add a guest device, tap on the button "Pair guest device" at the bottom of the "Devices" screen. A guest device can view the camera live feed and receive push notification, but cannot view the event history.