Download Exclusive-Black. It is the better version of Exclusive-Dark. On PHP8.1 and Xenforo 2.2.12, Exclusive-Dark has many compatibility issues. But Exclusive-Black is all good.
You cannot use PSD files directly. You have to use Photoshop or any other image editing software to open the PSD file and export it as PNG or JPG. Then do as @XenForo mentioned here: