Understood, but still need guidance...
Running Android 7.0.
Add Folder doesn't show the stick in its folder list under Internal Storage.
Added /mnt to no avail.
ES File Explorer shows under Local a list:
[Home icon] Homepage
[Folders icon] Device
[Download icon] Download
[SD Card icon] 0 (Because I have no SD card inserted)
[USB icon] USB1002 (Will change to USB1003 and so on if I disconnect and reconnect)
In short: how to add the stick to the library?