Terminal emulator in Android is giving me 'Permission Denied ... - reddit
To access your SD-card, go to /storage and find the folder with a name in the form of XXXX-XXXX, where X are random digits/letters. You may need to grant the app permission to access the external SD card, and it just won't work with some apps, so, well, you may have to switch your emulator to a different one if it doesn't work.