Probably the easiest way to run it is with Vinegar, a Wine wrapper for Roblox. You can just install it from Flathub (or Discover on Steam Deck in Desktop Mode), make a configuration file in terminal to set it to Vulkan and then you’re good to go after that:

mkdir -p ~/.var/app/io.github.vinegarhq.Vinegar/config/vinegar/ && { echo "[player]"; echo "dxvk = false"; echo "renderer = \"Vulkan\""; } >> ~/.var/app/io.github.vinegarhq.Vinegar/config/vinegar/config.toml

I know there’s a launcher called Grapejuice that’s very popular for running the game as well, but I don’t know if there are any additional steps needed to get it to work.