As discussed during today's GHE users meeting, the latest version of ArcGIS Desktop, 10.5, is available for LIB users from your usual software distribution outlet.
Desktop works best with ArcGIS Portal and Server 10.5, but it is backwards compatible so should work fine with Portal/Server 10.3.1.
Feel free to download it and give it a run and let us know if you see any issues.
Note to simplify/complicate things:
If you're new to the mapping game you probably want to use the Staff Portal instance at https://staff.gis.loc.gov or our ArcGIS Online instance at https://loc.maps.arcgis.com for your investigating. ArcGIS desktop is a bit more complicated and designed for more experienced map makers.
That said, feel free!
IT Project Manager
Geospatial Hosting Environment project
Library of Congress
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