. . . . I have previously done this and any attempt to initiate indicates that fact. . . . .
Assuming you mean when your first installed MEP 2015.
Try restarting your computer - Windows button, Power icon, Restart - not a shut down, this will reload all drivers etc then try exporting again.
If this is a re-install on a new computer
In Windows, Internet options are the items indicated below turned on - depending on your Windows version you may not have the later TLS version(s), if not turn them on, the start MEP.