How to transfer world from application to external (to copy it to server)?

I recently installed Minecraft PE v. 1.12.0.28 from the Play Store, and created a new world (in application storage).
My doubt is, how do I transfer it to a .zip file to upload it to Aternos.me?
When I search it in my internalstorage/games/com.mojang/minecraftWorlds folder it shows, but if a log into that world in MCPE (setup as external storage), I spawn far away from the place where I played on application storage.

It is possible to export worlds saved under "Application Storage" without rooting your device. You will need a Windows computer, a USB Cable and around 10 minutes, but overall it is quite easy. I have created a small program to make this even easier. The program works by using ADB's backup feature to copy all the Minecraft data from the device. The archived data is then extracted using AndroidBackupExtractor and the minecraftWorlds folder is moved from it.

More information and downloads can be found here.

(also, be sure to select External next time to avoid any problems)