Thanks to Praetorian for helping me out with the above, sharing the answer here in case anyone else has the same issue when they come here:

"Simply type "/" and press Enter in the "Add Game..." screen, in the address text box"

Hi there, I downloaded the APK of the latest development build of the Android port and I'm having trouble getting it to find my internal memory after installation , i.e. i can't add any files once I open ScummVM. How do I get it to point to my S9's memory?