It looks like in the past the tour bus got on a ferry in Kaupanger and sailed to Gudvangen. Now, it appears that route has been discontinued. Any body know where this year's tour will board and deboard?
You should ask Rick's Tour Department directly, since none of us will have a better answer. Contact info for them is here under "Guided Tours": https://www.ricksteves.com/about-us/contact-us
This year, the tour will board at Flam and sail to Gudvangen. The bus will not be on the ferry but will drive around and meet the group.
Thanks, Laura!