The game does not support Super Ultrawide 32:9 resolution. This was official stated here…
You might want to follow the suggestion advice so that such resolutions may be supported in future.
As stated previously, Super Ultrawide is an extremely unusual resolution as it is effectively 2 1080p displays side by side without discontinuity. Such resolutions are aimed at professional/creativity use where one might want the desktop area of 2 seamless displays next to each other. It certainly is not gaming orientated like 1080p or UltraWide HD is. To put it in perspective Steam survey throws Super Ultrawide in with Other, along with other unusual resolutions that few people have such as 8k.
I suggest playing at 2560x1080 UltraWide HD resolution. So that it looks good on your display, disable all scaling in the display pannel settings and NVidia graphic driver so that pillar boxing the left and right edges occurs to prevent ugly visual stretch. It should fill up ~2/3 of the display area in the middle of the display. You will still get a better visual experience than players like myself who play on a standard 16:9 1080p display.
In Windowed mode one might be able to use the other 1/3 of the display for other content while playing instead of wasting it with black pillar boxes. I cannot be sure as I lack the ability to test this.