As most of us here know and you just found out, the Dahua and Hikvisions of the world do not cater to the "consumer" market - their target audience is professional installers, so we are considered "prosumer" and we are fortunate to get our hands on these types of cameras instead of consumer grade junk and not having to go thru professional installers to get quality gear. Now the downside is we get them at a discount and without manuals and support and thus are on our own to figure it out. We are fortunate a forum like this exists to help with that. We do not exist in their world and that is their business model and they made the business decision to not compete with the Rings and Nests and Reolinks of the world and as such to do offer these cameras at box stores for consumers to purchase directly. They cater to the professional installers...and would tell you to contact the vendor you got them from if you have questions...
Contrast that with consumer grade cameras. You can call a Night Owl or Arlo or Reolink or Lorex or
Amcrest or DLink or Google Nest or Ring and speak to a representative (now whether they can help you or not is another story) and for most novice callers they provide good customer service, but they will not tell you to talk to Best Buy where you purchased it...and several of these cost the same or more as Dahua or Hikvision...
Someone here will come thru, but a specific model that is older will take some time for someone with experience with that unit to offer suggestions...