ACC format is used in a software called Accent Duo, which a dedicated word processing tool with translation capabilities to romanic languages. It supports export to DOC format, which is probably what acc to doc conversion represent and is searched by users that do not have access to the software, just got the documents. Nothing indicates that .acc files can be opened in Word or similar word processor directly, which means the only option is the original software.
Updated: October 24, 2023