Hacks Unable to open Kual on K5 (Kindle Touch)

Hello everyone, I just received a Kindle Touch (K5) as a gift, and I’m really eager to explore it by jailbreaking (JB) and installing KOReader like this


However, I’m facing a small issue with KUAL.
My kindle is in 5.3.7.3 firmware
I downloaded the K5 JailBreak (5.0.x - 5.4.4.2) | kindle-jailbreak-1.16.N-r19426.tar.xz and successfully jailbroken my device as instructed.

I copied the file KUAL-KDK-2.0.azw2 into the Documents folder.

When I opened KUAL on my device, I got the error message: ‘This item is not signed by an authorized developer.’

Can anyone help me with this?