Offline installer & pending administrator service update

First time using the offline installer (from 2020.2.4 to 20202.2.5) as we recently went to an offline environment for SolarWinds, hoping some of you with experience using the offline installer can chime in.   Running the pre-flight check  shows a pending update for the SW administrator service which prevents me from running the update. The link states the administrator service MSI is available at, however when I attempt to reach that link I get messages stating the site is unavailable.

So, the questions:

how do I get the administrator service updated in order to proceed with the offline upgrade? 

Are there any other "gotcha's" to look out for when running an offline upgrade on an offline environment?