Notably, there's a "free for non-commercial use" license that grants access to the entire RustRover IDE.
There's also controversy because JetBrains removed JavaScript/TypeScript support from RustRover right before this release, admittedly because they want to keep these features gated behind a paid subscription in IntelliJ. That wouldn't normally be an issue, except the IntelliJ Rust plugin is deprecated and doesn't have the support that RustRover does; so there's currently no single IDE that fully supports Rust + web projects, even though JetBrains could easily make one, and even though people would be willing to pay for it. The end of the blog mentions "IntelliJ IDEA Ultimate will include support for the Rust plugin for free" so hopefully they are addressing this; if they re-package Rust support into into IntelliJ but only as a paid plugin I think that would make most people happy.