For the game to continue past the invalid configuration message, you need to instal mcf42 through protontricks:

protontricks 825730 mcf42

If you want the game to run at a resolution higher than 1024x768, you need the HD patch mod, and for it to work you need to install mcf140:

protontricks 825730 mcf140  

HD patch: https://www.moddb.com/games/tzar-the-burden-of-the-crown/downloads/tzar-burden-of-the-crown-hd-patch-1280x720-1920x1200-ver-30

For the HD patch to work, you have to extract the contents of the zip to the game root folder, and run TzarSettings.exe before running the game through TzarRunner.exe inside the resolutions folder. To do so I renamed the original Tzar.exe to something else, and renamed TzarSettings.exe to Tzar.exe, ran the game through steam, changed the name back to TzarSettings.exe, and finally created a symbolic link to TzarRunner.exe named Tzar.exe

To do so just open the game files from steam, right click and open a terminal in that folder, and paste this:

ln -s ./resolutions/TzarRunner.exe Tzar.exe