Closing as won't fix. I think this is to do with the encoding of the AAC file instead of a problem with Edge or Construct 2. Chrome and Firefox can play the Ogg Vorbis files which loop seamlessly, but Edge (and Safari) only support AAC. Due to the fact AAC is patent-encumbered we have to rely on the AAC encoder built in to Windows instead, and that sometimes pads sounds with silence which adds a gap to looped sounds. (I checked the files in Audacity and the .ogg is 4.571s and the .m4a is 4.621s, so it does look like the AAC was made unnecessarily longer.)
You can try to work around this by encoding the AAC with a different encoder and re-importing it. However there's not much we can do to fix it.