Thank you Anil,
I included this in my csproj file, but it is still not solving my problem. I have tried so many variations of editing the csproj file but it always cannot locate PDFTronC.dll or one of its dependencies.
<ItemGroup>
<Content Include="PDFNetC.dll">
<Pack>True</Pack>
<PackagePath>\lib\net6.0-windows7.0</PackagePath>
</Content>
<Content Include="PDFTronDotNet.dll">
<Pack>True</Pack>
<PackagePath>\lib\net6.0-windows7.0</PackagePath>
</Content>
</ItemGroup>
Edit: I have also confirmed when inspecting my nuget package file that these files are being put in lib\net6.0-windows7.0 but they cannot be located at runtime