Hi again, Laminar Research strongly advises to first install with no scenery at all. That's only 7Gb instead of 70Gb to download and you can still test your simulator at KSEA or LOWI.
In your case, possibly, most of the scenery had already been downloaded, so I would just launch the installer again to update x-plane : every file will be checked in the process, so that your copy of X-plane can be completed and/or corrected.
Launch the installer as many times as required and tell us what you get.