How to add 3Dmark demo to Steam Library on Linux?

[Zaza]

I wanted to see if I can use 3Dmark on Linux, thought it probably would work fine just using Proton. However, the issue is that the 3Dmark demo only have a Download button. It does not have an add to library button, so I can add it and then set Proton to install it.

I only get that it is an invalid platform if I click on Download at the Demo page in the Steam store.

Anyone been able to add 3Dmark demo to library on linux before?