Trying to figure out subdomain redirection

My blog is at taonaw.com and it points to MB fine.
I want my wiki, which is on The Art of Not Asking How — Tech Voyages and Beyond to be pointed from taonaw.com/wiki.

OK, so on my domain registrar (cheapdomain) I have a URL redirect. If you type taonaw.com/wiki in your browser, it should work now.

But. When I change my wiki page at the nav bar (top right on taonaw.com) to point to taonaw.com/wiki, things break. It seems to be stuck in a redirect loop where the page keeps refreshing endlessly. This feels like it’s a basic understanding issue of how URL redirects work, and I did ask their support team, but they just direct me to articles that give me the wrong info (geared toward having the main domain redirected, not the subdomain).

I was wondering if anyone can shed some light? How do I do this seemingly simple thing?

Thanks!