Long story short, I've tried both methods of uploading a world onto the server, both on the website and the '/ul world' command.
The adventure map I'm trying to run is https://www.planetminecraft.com/project/mazescapist/. The map is
- Under the maximum size of 500 mb's (it's a bit over 200mb the map)
- It has custom resources (to change the texture of certain blocks)
- It has data packs
- It has multiple worlds
Here's a image of the zip file opened
here is an image of the unknown error message: