Allow respondents to download a fillable PDF document to fill in and upload then submit

I need to upload a required state document, have it filled out and signed, and then returned to me for a file.  

THis is the most important part, not necessarily gathering data...

How do I do this?

You can create a form and include the link to download your fillable PDF state document in that form, then add a File Upload field with instructions that your respondents should download the PDF document first and upload it in that field.

Here are the guides that may help you with your requirements.

How-to-Add-a-Downloadable-File-to-Your-Form

How-to-Create-File-Upload-Forms

Feel free to let us know if you need any further assistance.