Unity 3D : Settings for Android build game.

If you try to set the Android SDK on Unity 3D using the Linux O.S. then you can have a problem.
After you set the name of the package and the default android settings you can use External Tool from menu Edit - Preferences to set paths for Android SDK, NDK, and more.
This is the path I used to build with Android:

• /home/catalin/Unity/Hub/Editor/2019.3.5f1/Editor/Data/PlaybackEngines/AndroidPlayer/OpenJDK
•  /home/catalin/Unity/Hub/Editor/2019.3.5f1/Editor/Data/PlaybackEngines/AndroidPlayer/SDK
• /home/catalin/Unity/Hub/Editor/2019.3.5f1/Editor/Data/PlaybackEngines/AndroidPlayer/NDK
• /home/catalin/Unity/Hub/Editor/2019.3.5f1/Editor/Data/PlaybackEngines/AndroidPlayer/Tools/gradle

You can see the android SDK, NDK and Gradle is set on the Hub Editor This is my External Tools configuration for that build game: