That’s an old and slightly weak card (for Rust, not everything), unfortunately. However, the other part of it is, the experimental/“new” version of Rust (contrasting against the legacy version, which is basically a first draft and had work stopped on it in February) is pretty unoptimized right now, and people with beefy rigs are getting much lower performance than “expected”.
Expected is in quotes because, at this stage of the game, bad performance is something to expect, but the goal is obviously to have better performance, and rigs that should be able to easily achieve that better performance when Rust actually hits a 1.0 state are getting much lower performance right now.
But, practically speaking, I don’t think you’re going to get more than 30fps on that MacBook no matter what optimizations go into Rust. A four-year-old laptop is just not going to do well with new games (and games that aren’t even out yet).