Cannot load .NET assembly from NetDotCell example

I'm trying to follow the example on building .NET applications here,

https://www.mathworks.com/help/matlab/matlab_external/net-arrays-to-cell-arrays.html

https://www.mathworks.com/help/matlab/matlab_external/building-a-net-application-for-matlab-examples.html

1) In Visual Studio Community (Version 16.7.6) I created a new Class Library (.NET Framework) project and copied the source code from the example.

2) In Properties --> Project Properties, I set the Target Framework to .NET Framework 4.5.

3) I ran Build --> Build Solution successfully. It produced a file "...\NetDotCell\bin\Debug\NetDotCell.dll"

4) In Matlab 2020a I ran NET.addAssembly('...\NetDotCell\bin\Debug\NetDotCell.dll') and got the following error

Message: Could not load file or assembly

'file:///...\NetDotCell\bin\Debug\NetDocCell.dll' or one of its

dependencies. The system cannot find the file specified.

Source: mscorlib

HelpLink:

[David Perlmutter]

Also, when I run NET.isNETSupported I get true, and I am able to successfully follow this example on built-in .NET Applications

https://www.mathworks.com/help/matlab/matlab_external/using-net-from-matlab-an-overview.html