LaTex: how to add a line break in the titke

Question

I have a poster to do but the tile was to long so I tried to break the title into two lines.

I tried:

\title{2D Bipedal Walking Simulation with \\ Deep Reinforcement Learning}

and I also tried

\title{2D Bipedal Walking Simulation with \protect\\ Deep Reinforcement Learning}

but somehow the compiler shows the same error:

and I don't know what's going wrong.

And also, I used XeLaTex to compile the tex file.

Any help will be highly appreciated. Thanks!