So you have a plugin from the Unreal Market which is not updated for a higher engine/project version either the developers are slow to update it or, are not going to update it.
We will go over a potential on how to update the plugin now from the perspective of an engine plugin.
If you are using your current project as your test, we recommend not to do that and create a new blank C++ project for your engine. You should also install Visual Studio if you have not done so already – the community version works great – https://visualstudio.microsoft.com/vs/community/
Now the housekeeping is sorted
Create a new blank C++ project.
Locate the engine plugin at the following location “C:\Program Files\Epic Games\*engine version*\Engine\Plugins\Marketplace\*plugin to update*”
the “Program Files” folder may be the “Program Files (x86)” depending on your Windows setup.
In your project, make a “Plugins” folder (if you are not too sure, in the root folder, in with the Blue .uproject icon (image below)
Copy the plugin from the marketplace folder into the new Plugins folder of your project.
Open the project which should prompt you to rebuild the missing modules, or it may state that the version of the plugin was made for an earlier engine, do you want to run it anyway. You may have to compile from source which is why you made the C++ project. Open the solution in Visual Studio, and compile from there.