Basically none of these chinese FET based commodity BMS' have a true manual or even really a full product page from what I've seen.
You might get more of a response if you give a link to the BMS or more details. I believe DYKBhuang, is a
seller, not the manufacturer. It is likely that you have either the
JBD Smart BMS (JBD-SP04S020) or the
Ant BMS, but without more info hard to know.