When guests go through the onboarding process, they shouldn't have to choose an avatar, color scheme, etc. Just take them to the project/list they were added to and let them decide on profile options later if desired.
Also, maybe change the Play with ClickUp button text to something less playful since the guest wasn't invited to the project to play :) The current wording makes sense if a user is signing up for a demo, but not for a guest.