L.S. v4.2.1 Nightly-Build (5204), is apparently, in-compatible, with old-fashioned https://ara.apple.com screen-sharing, due to Code-signature-mismatch mishandling of Apple "Gatekeeper"-technology, in the High Sierra v10.13.6 O.S. .
The timestamp embedded in the name of the app, generated by the old-fashioned https://www.apple.com screen-sharing-download, apparently prevents Apple, from properly assigning the proper "code-signature", to the app, and this Nightly Build, does not properly re-direct, to the "Security & Privacy" "System Preferences"-pane/control-panel, to approve the app, in the Apple "Gatekeeper", technology .
The NIghtly Build, only offers the option, of creating a new rule, which gets the user, repetitively creating the same new rule, which doesn't seem to help the situation .