Getting started with the NetCore build requires you are using the latest nightly builds.
You will need to add the nightly nuget feed to your list of sources
dotnet nuget add source "https://www.myget.org/F/umbraconightly/api/v3/index.json" -n "Umbraco Nightly"
Clean the appSettings.json by Removing 'ConnectionString' section from the file
Dotnet build
Dotnet Run
- you will need a blank SQL Database (not SQLCE)
- install following the prompts enter db details when required.