Fine! So, I assume your animation is ok and safe.
The export settings looks ok to me. I never personally have the loop checkbox checked, since I animate one scene/shot at a time, and edit it in kdenlive (linux).
I have never experienced problems with VLC being unable to play a mp4 from Pencil2D. If it remains a problem, somebody wiser than me should come to the rescue 
Maybe you should try our Discord channel. There are people 'round the clock, https://discordapp.com/invite/8FxdV2g