Preferences are important --Installation of JAVA and setting of PATH Oracle Java https://java.com/ja/download/win10.jsp path setting (I also installed Java SE Development Kit 14 )
--Run Graphviz .msi without changing the installation destination (https://www2.graphviz.org/Packages/stable/windows/10/) Then set PATH Set the value up to dot.exe with the variable name of GRAPHVIZ_DOT
Install VSC Plugin PlantUML jebbs 2.13
I haven't changed any settings, but be careful not to add anything extra in stting.json.
-It took about 14:40 to 19:40, so I tried and errored for about 5 hours.
References  https://proengineer.internous.co.jp/content/columnfeature/5205  https://eng-entrance.com/java-install-jdk-windows