A curator is not an editor, however they can be authors in their own right. They are usually associated with works of art rather than with textual works, like the contexts and examples that are provided in the attached link.
There is no definitive statement regarding curators in APA 6th, however according to APA 7th (12.6)
Editors provide skills for refining and improving content. If the resource is a journal then the editor contributes to the content according to the journal's style guidelines.
This means a reference for a curator would have curator in place of the Editor in a reference.
For example:
Douma, M., curator. (2008). Calendars through the Ages. Retrieved month day, year, from http://www.webexhibits.org/calendars.
APA 7th: Artwork references
Curators are traditionally associated with physical or virtual exhibitions, in cultural settings like art galleries or museums. A relevant link with examples from the APA 7th Style & Grammar Guidelines is attached.
