How do you use the Update only download files to update the game? Just extract it then copy paste replace the entire folder into Renryuu Ascension existing folder?
I explain how to use the update files the video shown below.
In short, yes, you put the extracted www folder where the www folder is in the game folder, and overwrite the old files with the new files. But please make sure you have the previous game version, as skipping an update when you use the "update files only" will cause you to miss files from the updates in between. The version number and what the previous version was is always mentioned in the file name of the update file .zip.
If you skipped some updates since the last time you updated your game, the best way to update is to download the full game again and move the entire save folder content from the old game folder to the new game folder.
On android, you don't use update files. The newer .apk on android automatically updates the game to the newest version when you install it.