Critical error on page with timeline

After installing en setting up a timeline on one of my pages, everything on the back-end seems normal (all works and I see a functional timeline). When I open the page on the front-end, I get a critical error and the page won’t load. When I deactivate the Timeline Express plugin and then open the page on the front-end, all is okay.

I don’t know how to fix this.

The page I need help with: [log in to see the link]