FSGS uses LLFF dataset, but I found corresponding link and gdown command have no permission or give a 403 error.
And, I figured out mirrored link : https://drive.google.com/file/d/11PhkBXZZNYTD2emdG1awALlhCnkq7aN-/view, or you can see LLFF dataset in Kaggle https://www.kaggle.com/datasets/arenagrenade/llff-dataset-full/.
Instead of using the existing command, this command allows you to download the LLFF dataset:
gdown https://drive.google.com/uc?id=11PhkBXZZNYTD2emdG1awALlhCnkq7aN-
unzip nerf_llff_data.zip
I hope this solution helps you get FSGS code running π