UX/UI design of OAndBackupX, the backup app for Android

OAndBackupX (Shortly OABX) is a fork of OAndBackupX, the only open-source backup app for android in the last 4-5 years. The apps itself has already adopted a new design, that differs from the older one. Me having no previous experiences in the field of usability design, I still question the quality of the app in this matter. The community and I would be glad having a UX/UI designer on board.