I took a look at your account and can see this experience you're describing. I apologize you're not able to post your campaign as easily as you should! Does your post go through after clicking the "Want to send it now?" Were you trying to post when the email was still set to scheduled? I can also see the Facebook page connected looks like it may be a personal page. At this time Facebook no longer allows third-party apps to post directly to a personal Facebook page. If you are trying to post on a personal page, please connect a Business page instead.
Hello there @Lesley-AnneC !
I took a look within your account to see if I could find the social share post that was giving you the error, however I only an email campaign that is still in draft. Are you attempting to link your Facebook page in the email campaign or post the email to social media?
If you are attempting to link your social media accounts within your email campaign I recommend taking a look at this article, Insert or Remove Social Media Icons in an Email, which will walk you through those steps.
If you are trying to achieve the latter option, putting the email campaign you've created on social media using our social share feature; once you have finished creating the email and have sent it out to your contacts then will you see the option to put it on social media! You can do this either one of two ways:
Either way will let you share your email out! If you have any further error or are receiving an error then, please let us know. We're always happy to help!