When you need a component such as the .NET framework you can install it in Wine/Proton using the Windows installers. The .exe you are being recommended should be able to run, but the other way around it is to use something like protontricks, a proton version of winetricks (technically it uses winetricks and is more of a set of integrations and a GUI, but yeah). Using protontricks you can install the .NET framework, the C++ runtimes, dxvk, and other tools. I would recommend learning a little about how to use protontricks and maybe look for a few specific tutorials for using it with specific games to get a feel for it.
It is possible, can you confirm the filesystem your steam install is on? The T7 mount looks like an automatic user mount, is it a standard ext4 or btrfs partition? Also, why is it mounting there, not in a fixed location denoted in your /etc/fstab file? If it is just automatic mounting there are some possible issues that could come from that, it may be worth testing another windows game through proton installed in the same steam library folder.
That all said, you definitely need to have proton installed. If you go to your steam library you should be able to search for proton there. I would recommend installing the current version, the experimental, and if it is there proton-ge. I haven’t used Debian for a while so I don’t know what is in your repos but searching for proton-ge there may also have results.
Once you definitely have the latest and experimental versions try switching version, testing with protontricks. It should show up both versions and allow you to switch between them without problems. You may also need to define your proton prefix as an environmental variable, something like PROTONPREFIX=/path/to/your/T7/proton/prefix/
If you can’t get that going consider jumping on to a matrix channel for more second by second help, tonnes of people are happy to help you get wine/proton working correctly.