Adobe Sign and Fill Error: "You do not have access to this service"

[Daniel5C55]

I am trying to use the "Fill and Sign" feature of Adobe, but I keep running into an error saying that "I do not have access to this service." Steps to reproduce:

• Use a Macbook Pro laptop, High Sierra, version 10.13.6
• Install Adobe Acrobat Pro DC, version 2020.013.20064. I installed using my university account, which provides Adobe Acrobat (along with a host of other Adobe applications).
• Open a PDF with Adobe Acrobat. Make sure that the user name shown in the application is my university email (I click on the upper right icon to check).
• Click "Fill and Sign" to the right.  Click "request signatures" as shown in "picture1" attached here.
• Fill in the email(s) to request, then click "Specify Where to Sign" as shown in "picture2" attached here.
• Then the error appears. See "picture3" attached here.

Any ideas on how to fix would be greatly appreciated. Thanks!

[Daniel5C55]

It seems like I cannot download my attachments, for some reason. Here are the set of four pictures.