Navigate to the core login screen at /web/login. This template is shared by every Odoo installation (Community and Enterprise alike): it ships in the base "web" module, not the Website builder.
Examples
Given I am on the Odoo login page
Given we are on the login page
Given I am on the sign in page
And on the Odoo sign-in page
Given I am on the web/login page
Pattern
Given(/^(I am |we are )*on the (?:Odoo )?(?:sign[- ]?in|web\/login|login) page$/, …)
Part of @webship-js/odoo-steps (github.com/webship/odoo-steps), a step pack for Webship-js 2.0.x.