Other communities work fine and I'm able to subscribe. Just curious what could be the issue. Do I need to wait for the community to be made "available" on lemmy.ca?
You need to use the search function in the UI here https://lemmy.ca/search, not type the URL directly in your browser.
I just this for you and now the link works properly.
Just have in mind the first time you search for a community it might take a few seconds and a few refreshes to actually see it.
Lemmy.ml is overloaded and known for having this issue. Also, even if it says "pending" you might already be subscribed. I just saw this in my subscribed feed even though my subscription to this sub is still pending.
If you're the first person on your instance to subscribe to a Community on a different instance, you need to make your instance discover the other community.
You can paste the URL or !apple@lemmy.lm in the search field on lemmy.ca, then you should be able to find it on lemmy.ca -> Communities