Once you've installed BlueStacks, there's two ways to open the APK file:
Right click on HDIPTV.apk file and select 'Open With' > 'BlueStacks APK Handler'
Open BlueStacks app and drag the HDIPTV.apk file to the app. It should automatically install.
Use the following navigation:
Media > Open Network Stream > Network (paste the M3U link into the Network URL).
Toggle the playlist on the Control Interface to play channels (View > Playlist). Double click to watch!