OTG support for Samsung A3 Nothing happens when I plug a USB stick to my Samsung A3 2015 (SM-A300FU) with an OTG cable (on-the-go).

How to enable OTG support on this device?

PS: I previously had a 5.0.2 original, unrooted. I now have a rooted 6.0.1 Marshmallow (Build number MMB29M.A300FUXXU1CRA3, Kernel version 3.10.49-12877970, Fri Jan 12 20:48:03 KST 2018).
What seems after looking at the your device specifications and descriptions is that it doesn't come with USB OTG support out of the box.This is a problem with many of the OEM's nowadays. Some clear it out in their specifications, some don't and it gets back to the user who has to figure out himself. I would still suggest you to confirm whether your device possesses this feature, just download an application from the Play Store called - USB OTG Checker.This will let you know if your device has OTG support. 

Since this thing is kernel dependent and, your device doesn't support this feature out of the box, then the most probable solution you can do is root your device and look for a custom ROM with a kernel that supports USB host or you can even just change the kernel in case you don't want to change the ROM.