A common problem that we get with Cloud Drive Mapper is that a user receives the error: 'Unable to Authenticate.'
There can be a few different root causes for this particular error. These are the most likely candidates to check first:
1. Check the SP URL is correct and not misspelled. This is usually only a problem during a trial.
2. Is the application being "Run as Admin"? Cloud Drive Mapper should be run under the user context.
3. Is there a genuine authentication issue? Can the user log into Office 365 and access the mapped location through the browser?
If you check these and they all seem ok, the next step is to check the error logs. See Article: How to Obtain the CDM Logs for troubleshooting?
Occasionally you can see the exact cause of the issue from the logs, so it's worth a quick skim read to see if there's anything obvious you can do to solve the issue. However if it's more complex and you're not sure what's causing the problem, then please send over the logs to firstname.lastname@example.org along with a description of the problem and we'll happily help resolve it for you.