I was reading about the digitalWrite() function to try to understand what its parameter might be.
That page has a link to more more documentation about pinMode(). But the link results in a page that renders a kind of broken XML document that says I don't have access:
What do I need to do to get access to the documentation? I am logged into my account. Do I need some sort of subscription? Or maybe there's no testing going on for the website, and something broke, unnoticed ... ?
You already have it. Somewhere a link was broken when a web page was updated. They will have to fix it, it is a pain for you it is a problem they have to fix. It is nothing you have done, permissions you need etc. I get the same message.
Note that your link is https://docs.arduino.cc/language-reference/en/functions/digital-io/pinmode/, the pinMode that I did highlight above is https://docs.arduino.cc/language-reference/en/functions/digital-io/pinMode/; note the case of the word pinmode.