I don't know the exact reason you are experiencing this issue (I had many crashes trying to download the ones that were more than 500 MB so mine could be a similar issue but with a better connection / PC).
You can look for the games on their website (there's a button in the in-space description) and find out that most of them are available here, on Steam or even directly from their website, often as a pay what you want download or as a demo.
Also look if you have unzipped packages in the downloaded_games folder.