Use Dspline to Drive the liquid path Along A Spline
Add a Dspline modifier (Realflow>daemons>dspline) and drop the spline inside the Spline Object field. This daemon will drag the simulation through the spline. This is the first step to make the particles follow the path.
The viewport gizmo has the spline’s shape and red circles indicate the daemon’s control points. Circles around the control points represent the area where the daemon’s radial forces are active, helping the particles to be dragged along. Make your project timeline 400 frames long.