I don't know how to install the full res version, please help me how?
Open ZArchiver and find the file you downloaded (it's probably in the "Downloads" folder), tap it and select "Extract to ./<Archive name>/". After the process is done, go to the Downloads folder in which you should find a folder that has the same name as the file you just extracted from. It should contain 3 files, open the txt file for further installation instructions.
Both versions are same, but in the normal version, the quality of visuals and audio is reduced to make them fit in a 2GB .apk file, the maximum size allowed for this kind of file.
Installing the normal version is indeed a lot easier. However, as the game grows and more assets are being added to it, the quality will drop further since the 2GB size limit still remains. Sooner or later you'll have to go through the hoops anyway I'm afraid.