how do i subscribe to a kbin community?

Yes you can. Same as you do any other community. Find the one you want to sub to, hit the three buttons in the top right corner, subscribe.

Perhaps I asked the wrong question.
How do I get to the community in Voyager?
- Search a keyword, and several options will show up, choose the Community one.
  Keep in mind if no one from your instance has ever visited the community it won't show up in this search. Then your best bet is to visit it directly from the browser then subscribe to it (that's my understanding, somebody feel free to correct me if I'm wrong).
- When using Search, click the third option after entering your query.
  You can see below that a Kbin community shows up as an option.

This process works for any community whether it's on Kbin or Lemmy, and should work in any client including Voyager. It's the "correct" way that should work whether anyone from your instance is already subscribed:

Get the name of the community and the name of the instance. For example, let's say you want to subscribe to "NFL" on "kbin.social".
Put them together with a "!" and a @ to make an instance link like this: !NFL@kbin.social
Press search on your client and then search for that text.
One of the options will be a link to that community (but your instance's copy, so for me that will be https://discuss.tchncs.de/c/NFL@kbin.social). Click on it, and then click subscribe when it pops up.

Thanks friend. Much appreciated
This process needs to be a lot simpler. I can't tell you how many times I've had to do this for my partner (she just wants to use something other than Reddit but not technically inclined otherwise). If there was a prompt to fill it in for her, she'd be digging deeper into the fediverse.
Seriously - if we want any level of mass adoption, we have to design it more for the average person.
- The best solution I know for this is a browser extension. One that knows YOUR instance and recognises another Lemmy and so can put in follow links. There exists the equivalent for Mastodon, but not Lemmy AFAIK.

I think you can search for the URL of the community from where you're logged in. In the results list, you can then click on it to see it in details and click subscribe on the right. (That's the way I do it most of the time)

Just a side comment. Right now 5 out of 6 recommended communities are from kbin.social on the app

Thank you to everyone that replied with great answers!