From what we can see, it looks like your Sharing Link is getting truncated in the middle of the access code. Sometimes this happens if the text wraps and the user attempting to join only copies the first part of the link, or something could be formatting (or mis-formatting) the link you're sending out. Are you sharing this via email?
Going forward, while users providing partial access codes will still see errors when attempting to join spaces, the changes that @KarenMedina mentioned up above will make it more clear what's happening when a user encounters this kind of issue (and is not, say, running into space capacity limits). We're aiming to have that change out in the next week or so.
I hope this helps, and thanks again for your patience.
Mel