Home pages are like the first page your customer will land on when entering your store and usually the best products are presented there. these are the ones that can go out of stock quickly and having a "Notify me" button on them will be a huge benefit.
You can activate it in the Widgets section. select the Home Page button and toggle it on.
The button will appear on the Home page after being activated, as shown in the image below:
Note: If you're not seeing the button after activating it, we may need to make some changes. just drop us a line via our live chat or our email "firstname.lastname@example.org" and we'll take care of it in no time.