OBS Studio wasn't able to find a real GPU. This is either because you connect with rdp to this machine, or you do not have a valid graphics driver installed on this machine. Run OBS directly on the machine and make sure you have current drivers installed for your GPU.
In case you assume you do have current GPU drivers installed: uninstall them as thorough as possible, don't forget to reboot, download the most current one from the GPU vendor (usually Nvidia or AMD) and install again.
In case you connect with rdp to this machine: don't do this. It's not supported. If you must connect remotely, use vnc, because vnc just mirrors the display from the physical GPU, while rdp installs a virtual rdp gpu, which lacks the proper hardware acceleration OBS needs.