Just wanted to update this question with resolution. It might help someone else with the same problem.
I opened a Supprot Request for this. The first user that wasn't able to download was becaue of a pop up blocker. It stopped the "Save As" dialog box from showing up. After allowing pop ups from doucware, the "save as" dialog popped up allowing user to download the file. After this change, checking in the document also worked with no problem.
The other user that was having trouble was using Microsoft Edge for access to docuware. Help technician suggested switching to Google Chrome. Document checked in with no problem.
I find it strange that Silverlight will not work in Google Chrome (or FireFox) and Check in of versioned documents wouldn't work in Microsoft Edge. That means user has to access differing internet applications depending on what they want to do in Docuware.