I saw someone had started a topic previously and it seems that the installation is creating a shortcut for another version of a launcher that outputs the UAC request.
Go to this folder: C:\Program Files (x86)\Battle.net
Create a shortcut for the executable with the name “Battle.net.exe”. So not the ‘Launcher’ variant you will not get the prompt anymore.
If your start menu search launcher is asking for UAC as well. Go here and copy a shortcut to the previously mentioned executable: C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Battle.net
Hopefully if someone stumbles upon the same issue the google gods can direct you here.
Enjoy! 