Hope you are doing well and sorry for the trouble.
When you distribute a form, Acrobat automatically checks the form. If it doesn’t find a submit button, it adds a Submit Form button to the document message bar. Users can click the Submit Form button to send completed forms back to you. If you don’t plan to use the Submit Form button created by Acrobat, you can add a custom submit button to your form.
To know how, please go through the help page https://helpx.adobe.com/acrobat/using/setting-action-buttons-pdf-forms.html
If you see from my images (original post) I have created a Submit button that will (in theory) send the PDF to a SharePoint library. Is their programing or settings on the SharePoint side we need to consider?
The URL you submit to must specially be set up to handle submissions. If it's a general Sharepoint URL, nothing good will happen. There is no way to make a "submit" that just saves a file, without server-side programming.
What if it's a link to a specific SharePoint document library?
No, not even in theory. A submit is nothing like a save. You need a specially written web service/script.
Yes, I'd say that is missing some detail. I'd also say this was written over 20 years ago when the internet was a rather simpler place. There simply was no such thing as a web based file system. The only point of comparison was a SUBMIT from an http page - which is still the same, and also can't submit to anything like Sharepoint.
"To collect form data on a server, type the location in the Enter a URL for this link box. For example, http://www.[domain]/[folder]/[subfolder]/ for an Internet address or \\[server]\[folder]\[subfolder]\ for a location on a local network."
This is true. But if it said: "The URL must accept a POST request for the selected data format. No additional parameters can be set" is might at least indicate it isn't a filesystem. After all - where would it save? What name would it have? What about data privacy? What about credentials? These things are the job of the POST script.
Thank you so much for your expertise and insight! You've been most helpful! 🙂