You can install the name generator using your favourite NuGet client. For example using the dotnet cli:
dotnet add package KTNameGenerator.Core
Ther are two public methods you can use get the data for a particular faction.
KillTeam.FactionById(int factionId) or KillTeam.FactionByType(FactionType type)
For example to generate names for the Grey Knights you use the following:
var name = KillTeam.FactionByType(FactionType.GreyKnights).GenerateName();
If the faction you want has sub factions, like the Adeptus Astartes you can pass an optional param to GenerateName.
var name = KillTeam.FactionByType(FactionType.AdeptusAstartes).GenerateName(SubFactionType.ImperialFists);