If you run into the following error message that tells you that the Business Central server or NAV client could not instantiate an object, then this might be a signal that the control add-in files are blocked.
Cannot create an instance of the following .NET Framework object: assembly <assembly>, Version <version>, Culture=neutral, PublicKeyToken=<publicKeyToken>, type <type>
When you download the control add-in DLLs, then it could be that the execute permission for the files are blocked. If set up as a security policy, Windows will automatically block executables (e.g., .dll, .exe or .chm files) when they are downloaded from the Internet.
You can unblock the files by opening the Properties of the file and then check the Unblock checkbox at the bottom of the General tab in the file properties window. After that click on Apply and then on OK.
Could not load file or assembly