I just downloaded a custom park from this site and I looked up how I can install the custom park asset to the game. I tried forums and Youtube videos but none of them really helped. This game is from the Steam platform, so the file directory may seem different. How do I do this?

Put Your File in the folder called Parks.

Put Your File in the folder called Parks.

There is no Park folder on the Steam game

Put Your File in the folder called Parks.

There is no Park folder on the Steam game

If I understand it, it should be in your C:\Users\<username>\Documents\RCT3 folder. This is where your game saves are at. Make sure to download and install any dependent objects/textures into their respective folders.