de0u 79doosan I think it may be necessary to describe the problem with more details. Often it is useful to phrase an issue description as "I wanted to achieve X. I did Y, and I expected Z to happen, but W happened instead".
other8026 79doosan sorry, my response wasn't clear, so I've updated it. You can upload the pictures you want to share here on an image sharing website, like Imgur or ImgBB, then share the links to the uploaded images here.
fid02 79doosan When you open the APK file, you need to select "Open with Package installer" to install it.
other8026 79doosan In addition to what fid02 said, if you don't see the "Open with" popup, you may have accidentally set the phone to always open apk files with AppVerifier. If so, clear that setting here: Settings > Apps > All apps > AppVerifier > Open by default > Clear default preferences