Hello Dave,
OpenSSL libraries are required to use those Metashape features that use connection via Internet, such as direct data upload options, communication with Agisoft Cloud and the Basemap display in the Ortho view mode. For these purposes Metashape requires OpenSSL version 1.0.x (newer versions, like 1.1.x would not work).
If you do not need all these features, you can skip installing OpenSSL and just disable Show Basemap button in the Ortho view mode.