A disc is required?

[Chad Broski]

ok so i got red alert 1 right, anyway for some reason it says when i enter a disc is required, do i need one, because i just got it on steam

[Tore]

If it asks you for a disc then you might have accidentally disabled NoCD mode. I suspect you have tried to install the full version over the Steam version. This is not supported.

Uninstall the game on Steam

and follow this Steam guide. Then CnCNet and all it's upgrades should work.
https://steamcommunity.com/sharedfiles/filedetails/?id=3342972258

[Tore]

If it still doesn't you can enable NoCD by clicking "settings" in the launcher.