Hi Tim,
A.From your, Read this before installing Sticky:
Read this before Installing
2. Dot Net. With v4, Plan-G has migrated to Dot Net  v5.0. You do not need to download or install any runtime components, as these are all included in the program itself.\

B.From your Quick Start Sticky:
Plan-G Quick Start pdf.
The first time you run Plan-G, you will be prompted to install DotNet Core v3.1 (if you have
not already done so). Please be sure to install the x86 version.

C.The following was in your reply above dated June 01 2021.
2. Dot Net. With v4, Plan-G has migrated to Dot Net Core v3.1. The first time you run Plan-G, you will be asked to download and install Dot Net Core (x86). You should get automatically directed to the download page, but in case  you don't, here's the link: https://dotnet.microsoft.com/download/dotnet/thank-you/runtime-3.1.12-windows-x86-installer
INSTALL THE 32-Bit ("x86") VERSION!
Why change? This gives cross-platform compatibility, and a certain level of independence, which may become important down the road.

In my case, no request to download anything at initial start up.
I downloaded v3.1 from microsoft.
First flight connected ok.
Am i wrong to have installed v3.1? Can you explain apparent conflict in these instructions.
Sorry if this appears pedantic but it does appear confusing to me newbie.
Thanks and Regards.