All of her usernames and passwords are stored in Google Password Manager.
She needs to be logged into her browser as Marlene at all times to access those credentials. Look for the M in the upper right of her browser. If it’s there, she’s good.
For most sites, I will have already logged her in before delivering the computer, and she should stay logged in using cookies dropped by those websites.
If a site prompts for a username/password, Chrome will attempt to autofill with the stored credentials.
If that doesn’t happen, send Joe the details and he’ll get it worked out. The goal is that she should be challenged for username/password seldom or not at all.