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ULClient can be built using Visual Studio 2017. You'll need to download several updates after downloading MSVS 2017 Community. Specifically you need to make sure you have the v140_xp Windows SDK. You can download all the necessary SDKs from Microsoft's website.
You should also set the startup project to Underlight - not AgentSvr or AgentSvc.
You'll need the other Underlight assets in the target directory you're running the executable from (by default: C:/lyra/dev). Those assets can be found in this repository, under assets/