Hi ​@noelpd, thanks for your post!

The error message your customer is seeing when attempting to collaborate with you is due to the fact that your Lucid account, and therefore your document, are stored in a different data region than the one your customer is located in. Unfortunately, cross-region collaboration is not possible across data regions at the moment. For more information on this, I recommend reviewing our Data Residency Help Centre article.
 
As a workaround, you can make use of our Guest Collaborator feature to share the document. Since this is only available in Lucidspark, if you are trying to share a Lucidchart document you will need to take the following steps:
 

1. Open the document and navigate to File > Export > Lucidspark. This will create a Lucidspark copy of the document.
2. Open the newly created Lucidspark version.
3. Click Share in the top-right corner.
4. Select the Link tab.
5. Toggle on “Shareable link”.
6. Use the Users dropdown to select Anyone with the link.
7. Click Copy link.
8. Send the link.

 
Your customer will then be able to access and collaborate on this board as a guest. I suggest opening it in an Incognito window. 

Hope this helps, let us know how it goes! Cheers!