What is this Plexscape Server Login?

[JustinJohnston]

When I first load a map in ArcGIS Pro, I get this pop-up for a server login to http://www.plexscape.com/public_info/Collections/Placemarks/AutoCAD/pdmode0.png

I have no idea what it is, and clicking cancel instead of logging in doesn't seem to cause problems.  However, it does make me wonder what is going on and if my installation has some sort of error or problem that I don't know about?

Cheers,

Justin Johnston