You can download the scripts at the following address: https://free-astro.org/index.php?title=Siril:scripts
Installation from sources
Siril’s sources are available via git here https://gitlab.com/free-astro/siril/
But keep in mind that using the development version of Siril can be risky in the sense that it may become unstable at some point.
Choose your OS
Click below on your operating system’s icon to download Siril