Monsterley_128_s15_191104.zip is a release file of the Minecraft resource pack Monsterley HD Universal Add-On: Snapshot [WIP], made for Minecraft 1.15-Snapshot. It was published on November 4, 2019 and is 7 MB in size. For the full description, screenshots and every other version, visit the Monsterley HD Universal Add-On: Snapshot [WIP] resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.