Selected folder is not a Unity project

Hi,
I have a little problem with Unity (2017.3.0f3 64-bit). So, I tried to open an apk file in Unity. Then I selected a file and I saw an error message: “Selected folder is not a Unity project”. I reinstalled Unity, JDK, Android Studio, MonoDevelop and nothing. An error message still appears.,Hi,
I have a little problem with Unity (the newest version) . So, I tried to open apk file in Unity, then I selected a file and I saw an error message: “Selected folder is not a Unity project”. I reinstalled Unity, JDK, Android Studio and MonoDevelop and nothing. An error message still appears.

apk is an executable file for android and is not a unity project file. Only unity project files can be opened in Unity