An air-gapped server is a server without any access to external repositories or connections to any network, including the internet. To install Scylla on an air-gapped server, you first need to download the relevant files from a server that is not air-gapped and then and move the files to the air-gapped servers to complete the installation.
There are two ways to install Scylla on an air-gapped server:
With root privileges (recommended): download the OS specific packages (rpms and debs) and install them with the package manager (dnf and apt). See Install Scylla on an Air-gapped Server Using the Packages (Option 2).
Without root privileges: using the Scylla Unified Installer.