Hi Giselle,
Based on my knowledge and discussion with my colleagues, the issue is most likely related to the network environment or the Mac machines since the link can be loaded properly on a Windows computer.
Currently, to further narrow down the issue you encountered, could you please do the following tests?
1. Please use the affected users’ accounts to log on to OWA (Outlook Web App) with a Mac in different network environment such as at home to see if there is the same problem.
2. Please use a relatively fresh Mac to test if the issue persists.
In addition, please provide the following information.
1. You mentioned “When they click to log in”, are there the boxes requiring the affected users’ credentials or the logon page just can’t be loaded by different browsers? If the issue occurs after inputting the credentials, please use the test account I provided in the private message (your details > Private messages) to test the issue.
2. You said “going through the terminal”. Do you mean you run the command “ping outlook.office365.com” with the Terminal app in the affected Mac? If so, could you please provide the screenshot of the result here? If not, please run the command with the Terminal app to see if there is any error.
3. You provided some links in the second reply regarding troubleshooting OWA logon issue under the single sign on environment. What’s your exact environment, have you deployed ADFS or hybrid?
Thanks for your time.
Regards,
David