This app is built for the TP-Link HS110 smart plug.
With this app, your dryer or other non-smart appliance can send a message to your phone to tell you when it has finished, at least that is the way it appears.
It works by monitoring the smart plug energy usage and when it drops to a user specified level, a message pops up on your phone.
Your phone must be connected to the same wifi network as the smart plug.
Once monitoring has started you can exit the app and it will continue monitoring in the background.
The TP-Link Kasa app is very good but it doesn't make full use of the capabilities of the HS110 smart plug. This app doesn't either, but it does fill in one of the gaps.