APK android not install

I made a small project just to test the android apk generation. The apk is generated but when trying to install on mobile comes the message that “the application has not been installed”.
What would be the reason?
Android version 8.1.0
In the build configuration, it doesn’t include any permissions, because according to the documentation, what is indispensable is loaded by default. And this project is just a screen with a container and two buttons: one shows the container and the other hides it.
obs.: I noticed that the apk downloaded on the notebook has 47,122KB but when I transfer it to the cell, it’s 45.97MB

I had this happen before when my phone was running low on storage space. After freeing up storage space it worked.