Recently I installed the vCSA 6.0 for the first time. in prior releases it came as a .OVA file that could easily be deployed as any other virtual appliance. However when I downloaded the new version I was surprised to find that it was a .ISO file instead. I read that it is recommended to mount the ISO on a guest host, but that seemed annoying to me. So, I ended up using 7-zip to extract the files to a folder.
Then I ran the vcsa-setup.html file to start the installation. I did notice in some blogs they were calling it index.html, but I didn't have that option. From there the installation wizard will run. For the most part it's very similar to the previous versions. When the installation is done you end up with a vCSA appliance on the ESXi host your specified during the vCSA wizard.