I have an application that ingests scan data files that are manually fed. I would like to grant it access to our SharePoint site so it can pull the data automatically from a Document Library. What do I need from this application to give it the proper access it needs. The SharePoint site validates user account via Active Directory only.
SharePoint itself only "authorizes" account access so it has to be aware of the authentication source you use. In this case that is Active Directory. So any account you use must exist in Active Directory. The exception is if you have Anonymous access enabled - in which case SharePoint will grant access to any user or service requesting data from it.
The first thing I would consider is seeing if you can have your application make calls with an account that exist in AD that you can grant access to. If not,my recommendation here is to use a "middle" tier - possibly a server side script that runs at set intervals and passes those documents over to where your service can pick them up.