Hello @something12356, the download and installation of games through Steam is managed by the Steam client, not Proton itself, so I've transferred this issue report.
Blind guess that this is a one-off quirk. Can you check if a simple restart of the Steam client has an effect?
I've restarted the client a few times and it hasn't solved it, installation works fine for other games, I've even tested ones that weren't in my library previously, and they still install fine. The issue only seems to happen with forager.
I've tried it daily since I opened the issue, and today the game just installed properly for whatever reason, not entirely sure what happened.
Nothing extracted yet.
Compatibility Report
System Information
I confirm:
I can't generate a proton log because I'm unable to install the game.
Symptoms
I cannot install forager, when I click the install button a window pops up saying Install - Forager with a white box below it, there are no buttons to press, and clicking where the buttons to install usually are doesn't work either.
Reproduction
Click install on forager
https://imgur.com/a/yaK9aTh a screenshot of what the install window for forager looks like, and what happens when I try to install any other game I own.