installing itext 7 for the first time and trying out. It looks like a dll is not included. the "itext.commons.dll"

I get the error; You must add a reference to assembly 'itext.commons, Version=7.2.1.0, but there is no such file included in the nuget package for iText7.2.1.

I found a similar file "lib_net461_itext.commons.dll" and tried to reference it and then the project compiled, BUT then there arise problems with loading;

System.IO.FileNotFoundExceptionHResult=0x80070002Message=Could not load file or assembly 'itext.commons, Version=7.2.1.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. The system cannot find the file specified.

probably because I have the wrong "itext.commons" ??

Is any one that knows what is the problem?The code I am using is a sample from iText 7 introduction sample so that should be OK.