The recent edit I did of a sunset/storm after basic editing and rendered was only 9.2mb and 24 seconds long. 600 raw photos, 6 second between shots. Still it was too big to share via IG or FB. I did manage to get it up on Youtube. Would appreciate any assistance so I can share my work across social media platforms. I will try rendering after conversion of RAW photos to JPG sequence in LRC. Thanks in advance.
https://youtu.be/8HCL5FNJLaA

9.2 mb too big? Strange. LRTimelapse is rather designed to export high quality for further processing in Video Editing programs.
But you should be able to render an MP4 in 1080p with medium quality, 420, legal range, 16:9 and upload that to the platforms.