I'm trying to get the source code of an application to study its operation and try to make my version of the same APP from scratch. I have seen several ways but none of them worked on Ubuntu 18.04. I've tried it more times was a response found in stackoverflow, of which I show the link below, but in STEP-2, section 4, I can not get the necessary file created. Is there any way in Ubuntu to achieve my purpose? Thank you.
Link to the question why I have been guided:
https://stackoverflow.com/questions/3593420/is-there-a-way-to-get-the-source-code-from-an-apk-file