Apparently the model decompresses, and it won't fit very well on the 8gb models... I'm willing to give the max settings a spin on my 3070ti, but I'm not very hopeful.
It says that NVIDIA chips are recommended but that they are working on optimizations for AMD. This implies to me that it probably involves CUDA stuff and getting it to run on a Radeon would be potentially difficult (I am not an expert on the current state of CUDA to AMD compatibility, though).
AMD's answer to CUDA is called ROCm. I've been doing a little research on it since a few weeks ago and it seems to be funky when not outright broken. It's absolutely maddening that after all this time AMD doesn't have proper tooling on consumer GPUs.