Hiii nancy cuyle, perhaps the problem is with your subscribe page and its slug cant be found out..
Just follow this steps..
Activating the FOLLOW PLUGIN: 1. Installing and Activate Follow Plugin
Create a WordPress Page Called Subscribe THE URL ADDRESS OF THE PAGE MUST BE – “/subscribe”
Open the subscribe page (Editor) Click the ‘S2’ button on the QuickBar to automatically insert the Subscription Form.
and also dont forget to uncheck the Include this page in lists of pages(on right sidebar) go to WordPress DashBoard>>>>Pages>>>All Pages>>>Edit Subscribe Page(which you have created manually by inserting s2 button)>>>Uncheck the Show this page in navigation menu
more more help check this link: https://www.ads-software.com/plugins/follow/screenshots/
Go to Follow Plugin Menu (Listed Below the Settings Menu of WordPress) and then go to Settings>>Appearance and follow as written red letters.
Please let us know if you have any difficulty..