How to make the .data file smaller when exporting to HTML? (UE 4.23.1)

I am trying out UE4 (learned using UE5) so I can make browser games, and I made a very basic one to test - just the First Person template with the shooting code changed a bit. I tried to upload it as a draft to Itch.io and it told me a .data file was too large within the .zip I had uploaded. Any clue how to make it smaller for when I make an actual game?