Note from @MichaelTunnell:
this issue is not related to DLN but rather was local device issue for the user.
Maybe the DLN Discourse server is hacked? I immediately deleted the 4Play.apk file, and didn’t install it. It was a 1.5 MB download. I’m on Lineage OS 15.1, which is effectively Android 8, patched up to Sept 25th version. (Sept security update).
The .apk download spontaneously happened while I was composing a reply in this Discourse (like 15 minutes ago)! I’m using the latest Firefox for Android, ver. 68.1.1