Trouble Sharing Designs Created in Canva

When I'm logged into my Constant Contact account, I'm able to retrieve my designs created in Canva, but for some reason when I'm signed on to the Canva website, and I try to send my designs to Constant Contact from Canva I receive this error message:

"We were unable to publish your design, Canva experienced a technical issue while publishing your design.".

So I reached out to the Canva support team and they sent me this reply:

"Our team has confirmed that the issue is replicable on our end. We understand you’ve already reached out to Constant Contact for help, but could we kindly ask you to contact their support team again to confirm the exact file requirements needed to publish successfully from Canva to their platform?".

The Constant Contact help Canva is referring to is the Constant Contact chat I had with your automated chat box system, which sent me back to Canva to resolve this issue?

So can someone from the Constant Contact support team provide me with the exact file requirements needed to publish successfully from Canva to their platform (that the Canva support team is asking for) or any information I can provide to the Canva support to resolve this issue?