Hey there, like some people already said, the file you uploaded is not the build, it's the whole project / source code. You need to build the project. You can do that by going to File > Build Settings > Select your Platform (in the bottom left) that you want to build for, for example Windows. Then select "Build" in the bottom right. If you don't see a "build" button, click on the "switch to platform" button. it should take a little while and then you should be able to build it. After its done building you navigate to the folder and zip the whole build folder. You can also just look up a video tutorial on how to do that, for example this one:
Then you should be golden and everyone can playtest it :)
Btw. I managed to download your code and compile it in unity. The level looks nice and i noticed that you implemented a music switch depending on the biome / terrain that you are in. That's a cool idea! I also like the character model, did you create that by yourself? Currently the game is more like a walking simulator than a rpg, but the potential is there and I hope you keep working on it :)