How do you display Server Connect Set Value on the front end?

I have a conditional function which checks for duplicates in an import csv file and if there are duplicates found it sets a value “duplicates” = “Duplicates found!”

For good measure I have also set a Response = 200 to stop the server connect at the point of identifying the duplicates.

I want to be able to turn this value into a notification on the front end to let the user know the file they tried to upload contains duplicates.

How do I do this??

Thanks!