Many large-scale infrastructure and architectural projects stay in the version they were started in to avoid data migration risks. Revit 2019 was a milestone release that introduced several "quality of life" features we now take for granted. Key Features You Should Be Using:
Log in to your portal. You can usually access the current version plus five years back. Search results for revit 2019 (19)
If it’s missing from your list, the Virtual Assistant can often provide a direct download link if you have a valid serial number. Search results for revit 2019 (19)
Introduced the modern tabbed interface, making it easier to switch between floor plans and 3D views. Search results for revit 2019 (19)
Running software that is several years old requires a bit of extra care to keep it stable.