Did you this file from a specific developer or a tutorial?

Unless a developer actively publishes their .rbxl file or makes it "uncopylocked" for others to download, these files are only accessible to the person who created or downloaded them. 🖥️ How to Open and Explore the File

Because this file contains specific visual assets or custom scripts, you will have to view it locally to see what it actually is. You can follow these steps: Open the Roblox Studio application on a PC or Mac. Click on in the top-left corner. Select Open from File from the dropdown menu.