There is a link on bottom left "Trip Discussion". It brings me to a login page. I log on and then I get the following error message:
It is now October 2022 and I have encountered the same issue for my upcoming trip in February 2023, Living and Learning in Sevilla! Maybe each trip has to be requested to be "opened up"?
I think RS has stopped responding to this forum.
I noticed my Start A Discussion button gave an error until about six months before the start of the trip. I didn't report it, I just kept trying occasionally and in August (for a March 2023 trip) it started working.