Your PC probably doesn't have Vulkan support. To fix this, you need to create a .exe shortcut and add this command after the ("): --rendering-driver opengl3
obs: Make sure you downloaded version 1.1.2, as 1.1.1 is not working with Opengl.
obs2: Obviously you have to run the shortcut and not the .exe lol.
However, if your GPU supports Vulkan, try updating its drivers, if available.