The text here would appear to be confusing about what circular polarization means. Circular (or more generally, elliptical) polarization doesn't mean the light doesn't travel in a straight line.
Rather it means that the oscillations in the electrical (or equivalently, magnetic) field that the light consists of rotate around the axis that is the light's direction of travel, rather than staying in one fixed plane. The direction of travel stays constant though.
One way to think about this is to pick x and y directions perpendicular to the light's path of travel, and break down the light's oscillations into x and y components. Linear polarization occurs when these components are in phase with each other, and elliptical polarization occurs when they're not. When they're perfectly one quarter turn out of phase, you get circular polarization.
Rather it means that the oscillations in the electrical (or equivalently, magnetic) field that the light consists of rotate around the axis that is the light's direction of travel, rather than staying in one fixed plane. The direction of travel stays constant though.
You might want to see the Wikipedia articles: https://en.wikipedia.org/wiki/Circular_polarization https://en.wikipedia.org/wiki/Elliptical_polarization
One way to think about this is to pick x and y directions perpendicular to the light's path of travel, and break down the light's oscillations into x and y components. Linear polarization occurs when these components are in phase with each other, and elliptical polarization occurs when they're not. When they're perfectly one quarter turn out of phase, you get circular polarization.