Hey Randy thank you for posting in the Lucid community! Our sincere apologies for the delayed response on this thread - I wanted to follow up in case this answer may still be useful to you and to provide a solution for other users who see this thread in the future.
Previously Lucidspark used to have a 300 object per board limitation for users on free accounts which is likely what your collaborators were experiencing when attempting to add additional sticky notes. However free users now have access to unlimited objects! They will not experience this limitation when adding their feedback via stickies. For complete information on what is available to collaborators on free accounts please reference this Lucidspark Plans article.
Additionally you may find Lucidspark's Guest Collaborator function useful. This allows users on Team and Enterprise accounts to invite colleagues to collaborate on their boards - no Lucidspark account necessary! This Guest Collaborators article details this functionality further. Please let me know if you have any additional questions!