Download/install the free beta version from ...
https://www.scirra.com/construct2/releases/r242
You will need the beta a lot on the forums, most use the beta.
But, i never used the steam version, i assume it is not overwriting the Steam version.
If your steam version is still a free version, is say (boldly where no one has gone before) uninstall it, and get the free version from the source (this site). Steam is a nag (my opinion).