1. The mobile application will be synchronized with bpm'online upon first login. You will just need to input the web application address to log in. After this, the mobile application will start the synchronization process with the primary bpm'online application. After the synchronization process is complete, the application becomes operational. You can also use the mobile app in offline/online modes. In offline mode, the mobile application user should synchronize periodically with the main bpm’online application. Changes made to the mobile application are saved on the bpm'online server only after synchronizing with the main application. More details you can find here https://academy.bpmonline.com/documents/mobile/7-13/onlineoffline-modes
2. The access rights and permissions work the same way as in the web application. However, there is no option to set up the access rights directly in the mobile app. You will have to set up the permissions in the web application only.