The directory is created automatically when you start the app, so there’s no need to create it yourself. You can also have subdirectories in the latest version and they’ll show up in the file browser too.
The latest Android build is now available on Itch. Unfortunately I don't have any recent devices to test it on, but at least it seems to work fine on Samsung S7 edge.
Unfortunately I wasn't able to figure out what caused the error, but your save did have one uncollected secret item left in the fire stage. You need to reveal hidden blocks with Sonar Wave to get to it.
PS. I thought I fixed that typo already, but must have forgotten about it.