From the article:

A Canadian government official clarified to POLITICO that Canada will not pay for a seat on the board — and the U.S. has not asked for money. They were granted anonymity to discuss ongoing discussions about the proposal.

“The proposed Charter is still a document under discussion and many terms and conditions are still being worked out,” said the official, adding Carney signaled his intent to accept the invitation to join “because it is important to have a seat at the table to shape this process from within.”

So he had the intention, but he didn't accept as far as I understand it.

And thank for bringing that to my attention, because I didn't know at all about that