To install uSync.Complete you will first need to have installed Umbraco.
Install via NuGet Package Manager
- Package Manager
- Package reference
dotnet add package uSync.Complete
<PackageReference Include="uSync.Complete" Version="VERSION" />
Install as package
uSync.Complete v9 is only available as a nuget package, there is currently no way to install a package directly from the backoffice in Umbraco 9