Hey there, thanks for getting in touch! I'm sorry that you are unable to purchase Steel. Try deleting the cache folder, as this has been known to cause issues previously:
• Close the game and Steam.
• Navigate to the appcache folder in your Steam installation files (by default, this will be in C:\Program Files (x86)\Steam\appcache).
• Locate the folder named httpcache and delete it.
• Restart Steam and the game and try again.
If the issue persists, could you please provide a screenshot of the exact error message so we can investigate further?