I am trying to install SW2018 SP3, but I am encountering an error. It is telling me that I lack the required files for the install, and that they must be downloaded. A screenshot of this error is attached. I looked it up, and I read that the solution to this problem would be to not only install, but to download and install. But this option is greyed out, and I cannot figure out how to fix it. A screenshot of this is also attached.

How can I proceed with my installation?