Hello,
Many thanks for your post.
I found both files in WSUS, with a right click on the upgrade package, selecting "file Information"
I also tried to install it on a computer and found the same files in C:\WINDOWS\SoftwareDistribution\Download\SomeUID"
I removed step 11 as it is related to your anti-virus and replaced ESD with 1909 (also replaced all 1903 in your script)
also modified last step to stop success and failure.
Works well !