Ive never used AEL someone else will have to help you with that I'm affraid, like I said in another post, I came from retropie that's why I chose the emulationstation approach as I know how it works.
I have given more than enough information to get you playing games.
If you already have roms following my instructions using emulationstation and retroarch you would be up and running within 10 minutes if you follow it correctly.
It really is that simple.
Example for running everything from SD card
1. Install gamestarter repo
2. Install retroarch and emulationstation
3. Download libretro full cores from the configure menu of the retroarch addon
4. Launch retroarch, exit then reboot
5. Copy bios files to /storage/emulators/bios.
6. Create a directory called psx in /storage/emulators/roms/
7. Copy your psx games to that folder in iso or cue/bin format.
8. Launch emulationstation pick your psx game you want to play and that's it your playing psx games.
It's that easier, it only gets complicated when you want to customize things to your liking.