Please use the below download link for updating Lightroom to 6.3 Version.
You can try create another user account on Windows and use that account to update Lightroom.
I am trying to re-install LR 6.0 standalone but cannot get past Windows
indicating that Adobe Application Manager has stopped working. I can
access my Adobe account and see the details of my Photoshop applications
and their serial numbers as well as download the products again from my
order history. Tried again without my Norton Security and same result.
I have successfully installed LR 5.0 from the original disks and updated
to LR5.7 without issue.
I have uninstalled LR6 and PSE 13. Trying to install results in the
same problem. During install I am asked if I have already purchased or
want to try a trial. As I have already purchased these products I select
the first option and am asked to sign in. I then get a Windows message
that Adobe Application Manager has stopped working.
How can I get past the problem with the Adobe Application Manager? I
have used the Adobe Cleaner Tool to no avail.
Finally re-installed LR6.0 and PSE13 after reinstalling a fresh Creative Cloud app (not sure why it didn't re-install earlier). Used your download link to update to LR6.3 successfully
Thanks for your help.
Well, that's Great..Bruce