I had this problem and was due to not having an account created in Configuration → Network (on sidebar) → Advanced settings → ‘enable onvif’ (wait for reboot) → ‘add’ (within User List)
you should then be able to use this new user in the onvif intergration
I had the same issue and for me it turned out the password I had set wass too long or to be more precise: I generated a 20 char password, but the Annke (Annke is just a rebranded Hikvision) NVR (ANP800 (N88PCH)) only allows up to 16 chars. So when I pasted it, it cut off four letters but I pasted the full 20 letter password into HA Took me a bit to figure that out.