No, because Airbnb is sharing market information with you, and is quite happy for you to undercut the market to drum up demand, or raise prices if you think you’ve got a winner, which keeps market efficiencies intact.

What’s described in the article is a bunch of estate agents agreeing to use a price recommended by 3rd party software and minimize cheating on that price, which is price fixing.

How so? Is Airbnb colluding with competitors?

I think Airbnb recommends a price to set your place to? I know there's also some external software that do that too.

Based on the understanding of the post, I think both of those would be considered price colluding.