First, the path variable would just contain file name and not the full path. For that you would have to use Server.MapPath instead to resolve the path of the uploaded file. Which means you would have to store the uploaded Excel files in a specific location on the server and only then you can do a Server.MapPath.
Second, for your specific error this is what Microsoft has to say about it: Could not find installable ISAM
Finally, as a suggestion, try not using this approach to import Excel data because you cannot guarantee if Excel would be installed on the server. This code would need Excel installed on the server to work. As an alternative, I prefer copying and pasting Excel data into a text box and on the submit or save button click, parse this delimited data into a list and then iterate over it saving each record to the database. This way you can easily control the execution and provide more robust error handling mechanism.