EWS not connecting on Mac

I am unable to connect to Exchange on my Mac, with the same settings that work fine on Windows. I’m highly confident my settings are correct, but it always fails on Mac only. Log is below. I am evaluating for purchase for Mac. Thanks!

4:24:18 PM test [Exchange Web Services]  Synchronizing folder list
4:24:18 PM test [Exchange Web Services]  MailClient.Accounts.ConnectionException: Couldn’t get server version.
4:24:18 PM   at MailClient.Protocols.Exchange.ExchangeAccount.get_ExchangeService () [0x0001e] in <84a12a6f598a461499e0c1741cd38ac2>:0 
4:24:18 PM   at MailClient.Protocols.Exchange.ExchangeFolderSynchronizer.GetFolderList (MailClient.Storage.Application.Folder homeFolder, System.Threading.CancellationToken cancellationToken) [0x0000c] in <84a12a6f598a461499e0c1741cd38ac2>:0 
4:24:18 PM   at MailClient.Protocols.Common.FolderSynchronizer+<>c__DisplayClass10_0.b__0 (MailClient.Commands.WorkerStatus status, System.Threading.CancellationToken cancellationToken) [0x0001e] in :0
4:24:18 PM at MailClient.Protocols.Exchange.ExchangeGenericCommand.Execute (MailClient.Commands.WorkerStatus status) [0x0001b] in <84a12a6f598a461499e0c1741cd38ac2>:0
4:24:18 PM at MailClient.Commands.Command.Process (MailClient.Commands.WorkerStatus status) [0x00012] in :0

I have verified this issue on multiple macs/multiple different internet connections. Is there anyone from support who can help me? I am hoping to purchase several licenses but it needs to work on Mac.

If you require a response from eM Client Support, you will need to first purchase a Pro License, and then open a support ticket with them. (Chicken or egg situation for you, Joshua?) Otherwise this forum is the only option, and support here is provided by other users. 

I am not using the Mac client, so unfortunately can’t offer any suggestions besides making sure you are using the latest version available in the Release History.

Thank you, definitely chicken and egg…

In case anyone else has the same issue, it seems to be because the Mac version does not support NTLM or SSO authentication.