Troubleshooting C# Custom Class Library Nuget Package Installation

Hello, I have seen various posts and documentation regarding the creation of custom activities and adding them as nuget packages to be used inside of UiPath Studio. I have created a custom class library which I want to install as a nuget package to be used instead as a Type or Collection. Can someone please explain the differences in setup of the nuget package compared to setting up a custom activity? I am assuming the assembly reference will not be System.Activities but not sure where to start, thanks.

I just wanted to add that I have the package created and I can view it in the Manage Packages section. My current issue is that when I install the package, it appears as a red icon instead of blue and says “Requested = 1.0.0, not resolved”