For all those who are getting the error app not installed
It's because the app is trying to install it's self on your SD card
(If not this fix is not for you sorry. But you can still try it maybe it works)
So what to do ...???
1.You Could Just Remove your SD card And install the game....
(It still doesn't install in some cases)
2.Edit the package with an APK editor
  Steps
  Go to TapTap Settings >Click Install/Downloads >Turn of auto delete APK
  Than try installing then follow the below process =
  Download APK Editor
  Open the app >Click Select APK file >Click Android >Click Data >Click com.taptap
  >Click Files >Click Download >Click taptaptmp
  >Click com.tencent.aceforce.2456.apk(the file may vary due to device)
  >Click Common edit >Click Install Location >Click Internal Only >Click Save
  >Sys _Working..._ >Sys _Succeed_ >Click Install >Sys _Instaling_ >Sys App Installed
This is the method which worked for my friends it may work for you as well
(This method may not working for everyone)
If you have some issues or you know to fix issues help eachother in the comments
Thank you
Regards
X24D
i did everything here and still couldnt install the app help please. i dont have any sd card on my phone my phone is redmi 6 china rom
2020-11-02
Author likedwhich country are you from
2020-11-02
I only have this...
2019-08-25
hmmm I'll look into that
2019-08-25
The apk editor trick are useless its gonna be consume all of your storage in your iternal. The game is on 1GB up if you read the instruction on using apk editor they will gave you caution when modifying High Mb Games.
2019-08-20
I'm not a professional but I'm using this thing like Root ,Macro , Editors for quite a long time now I have given my opinion to fix it because I have done it my self Thank You
2019-08-21