i just set it up with the fill settings in the app. hit the 3 lines, then settings, form filling, and then select default auto fill.

you will have to enable it in phone settings to allow it to do so. but then you should be good to go.

i use KeepassDX. its amazing and simple and I absolutely adore it.

its going to be my password manager of choice going forward. i was able to set up my fingerprint unlocking as well. very convenient.

highly recommend it.