When the program indicates that Structural column or framing families are missing in the Revit Installation, the user will need to install additional content packs.
Below is the download link for Revit
https://www.autodesk.com/support/technical/article/caas/tsarticles/ts/24e0wvcXEokcfVbvUZtezv.html
This is also explained in CSIXRevit ReadMe file as shown below:
The link below from Autodesk provides further explanation
Install additional Revit content libraries | Revit 2020 | Autodesk Knowledge Network
After installing the Revit content libraries, make sure that Revit knows where to find them by running the Revit command Options, and then the File Locations tab, and then the Places… button.
