Okay, I give up on creating digital signatures. People can simply enter their name in the form field and return it to me -- these are all interoffice communiques.
I sent the form to myself, opened it, filled out the two fields, hit the submit button and received it successfully.
The two other people I'm seeking to fill out the fields are saying they're getting an "autoreply that states it didn’t go through," after they fill in their name and then hit the submit button.
Again, it successfully submitted when I tested it out.