First time using it you export your password data and move it into BW. Then browser extension can help auto fill and detect new ones. It also has a password generator built in so that’s handy

Phone app can integrate and auto fill. On iPhone I’m not sure it if can detect and save. But the few times I’ve needed to sign up on phone I manually input.

I still use Firefox password and iCloud saves when prompted. Doesn’t hurt to have a backup I suppose.