Gurobi now provides an officially supported NuGet package which is listed on the NuGet Gurobi Optimizer package website.
The probably easiest way to obtain the Gurobi Optimizer NuGet package is to use a package manager such as the NuGet package manager in Visual Studio. An alternative way would be to modify your .csproj file. In order to automatically reference the latest NuGet package of the Gurobi Optimizer, you can add the lines
<ItemGroup>
<PackageReference Include="Gurobi.Optimizer" Version="XX.*" />
</ItemGroup>
to your .csproj file where XX in the Version property refers to a Gurobi Optimizer version greater or equal than 10. You can also look at the example file gurobi-nuget.csproj, which can be found under <installdir>/examples/build/DOTNETCore2. Depending on your setup, it is possible that you have to install some sort of a (NuGet) package manager first.