store locator is no longer supporting the upgrade that allows you to import csv files but store locator plus is.
https://www.cybersprocket.com/products/store-locator-plus/
There is a charge for it but only $10 US.
You will also need to allow uploads of csv files to wp
See details here
https://redmine.cybersprocket.com/boards/33/topics/364?r=421
