Thanks for your question and I am sorry to hear that you are experiencing that issue. The most common causes for the M201 error include connection issues separate from our app, an overzealous firewall, and certain antiviruses - usually the Panda Dome Antivirus on Mac.
If none of those issues are applicable to your situation then I would recommend trying to access these two slightly different versions of the same site. Here133 and here133. Both need to load and be accessible on the Mac in question for our software to load and connect properly.
If the issue persists after that then I would recommend calling in for some more in depth troubleshooting and gathering logs from your Mac if need be. You can reach our Member Care Team at 989-720-8000.
Thank you and have a great day.