Please note that the Secure Password Sync Automation is not required unless you have multiple sites running Memberium and you want to allow your users to have the same password across all of your websites. If that is the case, you can check this documentation article for a step-by-step guide.
The Secure Password Sync Automation allows you to select an ActiveCampaign automation that will run when a user updates their password in WordPress.
This automation should be used to run the contact update webhook to push the password hash to all your other synced sites. Read the linked article above for a full explanation.
The Secure Password Sync Automation option needs to be used along with the Secure Password Sync Field.