Hi there thanks for posting in the community!

If you share a document with someone that doesn’t have a Lucid account, they will be directed to create a free Lucid account in order to access the document. Alternatively, you can Publish your document if you want to share a document for viewing without requiring login. 

Collaborators are limited to the offerings available to the account level they are on. For example, if you are on an Enterprise account and share a document with someone that creates a free account, they will have limited ability to edit the document even if you select “can edit and share” permissions. This is because free users are limited to 60 objects per Lucidchart document and do not have access to advanced features in Lucidchart documents or Lucidspark boards. Refer to our Lucidchart Plans and Lucidspark Plans articles for specific details on which features are available based on the user plan.

If you are on an Enterprise account and using Lucidspark boards, you can also create a Guest Collaborator link to allow users without a Lucid account to collaborate on your board.

Hope this helps!