Then make it easier for her to retrieve a password. A vault is not a good place. Give her a little notebook she can put in a shelf or drawer.

This, and it should be passwords she chooses and can remember (at least the ones she uses the most). Not some random mix of letters and numbers.

Also let her save them in her browser.

I don’t mean to be rude, but maybe stop forcing her to use a tool that you like but she doesn’t. I’m tech savvy but I also think that password managers are a pain in the ass to use. Just let her choose a password of her choice for every service, give her a little paper notebook and let her note down all the passwords. Tell her to make them long and secure and different for every service. Tell her to store the notebook in a safe place. Done.