If you experience a crash, un-installing and re-installing SZapp should resolve the issue. If not, try the following:
1. Tap and hold on the App icon, then click 'App Info'
2. Tap 'Force Stop'
3. Tap back and then tap 'Permissions', ensure permissions for 'Storage' are enabled.
4. Tap back and then tap on 'Storage'. Tap 'Clear cache' and then 'Clear data'.