Submitter not in the authors can't add editable

I have been contacted because a submitter can’t add editable. I checked the abstracts he submitted, he’s not in the list of authors (he confirmed that he submitted on behalf of his colleagues) and none of the authors has an email in authors list.
In the call of abstracts settings, “Allow editing” is set to “All involved people” and “Contribution submitters” is set to “Speakers, authors and co-authors”, there isn’t submitter.
I may add him as a co-author but that’s not right.