BLX is dependent on multiple packages available in standard repositories. If you do not have internet access, you'll need to create a private repository that has all the dependencies or install those packages before installing BLX. The list of dependencies can be found in the documentation page at "https://docs.citrix.com/en-us/citrix-adc-blx/current-release/deploy-blx.html#auto-installed-dependencies-for-citrix-adc-blx-appliance", under the section "Auto-installed dependencies for Citrix ADC BLX appliance".
