Eldiron is written in Rust, to run it you have to install Rust and its package manager cargo. Please follow the instructions on this page.
After you successfully installed Rust, clone the repository (or download the source via a .zip file), open a terminal, navigate to the Eldiron directory and start Eldiron Creator with
cargo run --release.
Once Eldiron is in pre-release it will be available on its Steam page.