How can I get "location check in" on mobile jotforms?

If you want to get location of your users you can use widgets like:

Get Visitor Location

Geolocation

GPS Location

IF I did not understood your question correctly, please explain in more details what you are trying to achieve. 

Let us know if you need further assistance. 

The idea is to have it function similar to Yelp where you can 'check in' to businesses such as restaurants, clubs, banks etc.

The end game is to have a pop up stating 'you are now checked in at XYZ business' and then launch a form.

I am not exactly sure what exactly are you trying to achieve. 

It is now possible to add popup massages to the form. You could embed your form to your webpage with full source code and add custom script that would do this. However this is out of our scope and you would have to hire a developer to do it for you. 

If you want to show some messages on your form, you can use text fields and show and hide them with conditional logic. 

How to Show or Hide Fields Base on User's Answer