That is almost certainly where you're problem lies. That CPU was released around 12 years ago and is not anywhere near meeting the recommended computer specifications for Vegas Pro 21, which are listed in: https://www.vegascreativesoftware.com/us/specifications/#productMenu
Though not given presumably the computer's GPU is of a similar age.
I'd be very surprised if you can get the AI Deep Learning Models to work with your computer given that I couldn't years ago (Vegas Pro 19 probably) with an Intel 4th gen i7 with an AMD RX480 GPU.
Maybe its time to think about acquiring a new modern computer.