This issue happens when the network drive or folder is currently mapped using a different username and password. This is further explained in the Microsoft article: Error message when you use user credentials to connect to a network share from a Windows-based computer: "The network folder specified is currently mapped using a different user name and password"
As a workaround, you can check the property of the Shared directory being used and make sure that it is configured to have a maximum allowed limit.
In this screenshot, the "C$" is the one used for the Shared directory, where support files will be copied during SMEX installation.
- On the target exchange server, go to Start > Administrative Tools > Computer Management console.
- On the Computer Management console, go to System Tools > Shared Folders > Shares. Right-click the C$ share name and go to Properties. You will be prompted that the share permissions and file security cannot be set when you try to open the Properties window. Click the OK button to open it.
- On the Properties window, make sure that the User Limit is set to Maximum Allowed.
- Click OK to save the changes.
If the above steps did not resolve the issue, use the target exchange server's IP address, instead of the server name or FQDN, when specifying the "Computer name" to install SMEX.