A problem with modifying the Android application

Hello my friends, can I find someone to help

There are many modified Android applications and I want to modify the WhatsApp Plus application

I tried to update the whatsapp omar, but I did not succeed in that. There is an error when performing the application assembly process using APKTOOL

I have also tried repeatedly to modify the ,whatsapp gold version, and the method did not work

Where can I find an educational lesson to modify the WhatsApp Plus version?

https://www.bramjdow.com/2020/08/whatsapp-omar-2020.html

https://www.bramjdow.com/2020/10/whatsapp-plus-gold-arab-WA2Abo3rab.html