If you get the Failed to create directory message with error=3 when starting Roblox on your Windows PC, use these proven fixes.

Lastly, click on the OK button to save changes. Read: Roblox won’t install or download on Windows. 7] Reinstall Roblox. If none of the above solutions work, you can uninstall and then reinstall ...

Click the green play button, and a popup will appear. Click "Download and Install Roblox." Once the download has been completed, open the downloaded file if the computer does not do it automatically.

Head over to the Roblox website and create an account for yourself. Then all you need to do is click on the 'Avatar' tab on the left side of the screen, where you’ll see your avatar ready to go.