The OnePager Pro portion of your OnePager Bundle includes a direct connection to Project Server (2007, 2010, 2013, 2016, and 2019) and to Project Online, including Project Pro for O365. This direct connection lets you build timelines from one or several project plans without having to use Microsoft Project on the desktop as a go-between.
To do this, start OnePager Pro and log into Project Online or Project Server. Once logged in, grab as many project plans as you'd like to show on your timeline:
OnePager will log into Project Online or Project Server, import your project plan(s), and generate a timeline automatically.