I was able to resolve the [AIO:ERRO] tc contains malformed auth token - expecting: {header: value{\r\n|\n}}* issue.
Page 9 of the Seeed procedure shows the API key being entered without whitespace following the colon.
Adding a space following the colon fixed the authentication problem. The working format using a faux API key -
Authorization: 1231234413091203u0980941092480914810481308013
I removed the whitespace a few times to verify resolution. Authentication would fail without the space. Hope this helps others.