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The two update packages you mentioned are correct.
windows10.0-kb4508433-x64_c4d6ffb6ee72a39da6c6c7e15a47d6e1520030e4.msu
windows10.0-kb4505903-x64_af8c6ab868423055a750797b6d52c1bd67e15a95.msu
What I wonder is your system’s version, type winver in Run dialog and hit Enter, what the build of your system now? These two packages are only for 1903 version. If you are using 1809 as me, you will see this message…