It might have something to do with the names and creating folders.
Are there blanks in the Excel document, like blank rows that would cause an error?
Do you have folders that would have duplicate names like two employee's named John Johnson?
Does the Department or the Names have any special characters or values that could cause naming errors like periods. or parentheses?
Did you refresh your browser to show the document library? Sometimes there is a refresh to show new items, and to see the new items in a file explorer might take longer.