Here's my case response in case anyone else is having the same problem:
"This is a known bug reported by other customers as well. I will attach this case to the list of cases for this issue. Our backend engineers are currently working on this fix and I will update you as soon as it becomes fixed."
In the meantime, I was able to download the agent executable (option B) and get that machine into Systems Manager using a thumb drive. I found that this option to be much easier and quicker than the email link method.