Windows should also disable Windows Defender when you install another resident antivirus.
Stopping it for the installation may be the issue as Windows should as I said " disable Windows Defender when you install another resident antivirus."
So I don’t know if your disabling it for the installation prevented windows automatically disabling it. Having two resident antivirus programs are going to fight like two cats.
Your question seems unrelated to this topic’s subject, other than having an installation problem.