Hi AJ thanks for posting in the Lucidchart community! I'm sorry for the trouble and I'm happy to help! You've taken the steps on your end correctly - you simply need to click "accept invitation" and this should open the document within your account - you'll also find it in your "Shared with Me" folder. 

However it appears that you are on a separate account from your students. The error message you are seeing is the result of a security setting that prevents sharing a document outside of the account in which it was created. If your students are part of an enterprise account the admin of that account can enforce a setting that allows sharing only among the members of the account. In this case you will either need to join the account to see the document or the admin will need to remove this restriction. 

If you have additional questions about this I would be glad to take a closer look at your and your students' specific accounts - please share more information in this thread so our support team can take a closer look!

Why would the email invitation functionality be enabled on free and personal accounts, when it requires team or entreprise accounts to function?

If you need to be a member of the account to view the board, and free and personal accounts doesn't allow members, why allow this function when it doesn't work.

It makes for awkward interactions with clients and colleagues.

Hi @tiniuslonot, thanks for reaching out and continuing this post, and apologies for the frustration. I would like to further explain this behavior for you! To clarify, sharing directly with colleagues via email invitation is possible for any Lucid user, regardless of account type. Any user on any type of account can share with any user on any type of account - a team or enterprise account is not necessary.

What you are seeing in this notification above is a security setting that enterprise accounts can enable, which restricts sharing to only other members of the account. This does mean that anyone outside of the enterprise account will not be able to access shared documents. There are two options here:

• Disable this security setting so that you don’t have to be a member of the account to view the document. This allows any Lucid user, including those on free or personal accounts (such as other colleagues or clients), to view it. 
• Adding anyone who needs access to the documents to be a part of the larger enterprise account. This means that individuals will no longer be on separate free or personal accounts, but part of the larger organization which is enforcing these security permissions. 

I hope this clarifies the situation. Please let me know if you have additional questions! 

I’m having this problem as well.

You say I can disable a security setting but don’t explain how to do that.

Very frustrating!!!!

Hi @RickMoore It looks like you replied to this post as well, please refer to that post for assistance: