You could use the font suggested on the style-guide.md by importing it from Google Fonts!
Go to the font page from Google Fonts.
In the 'Styles' section, there are different types of weights. Select the ones that the style-guide.md suggests. When selecting a weight, a drawer will show on the right side of the page.
Go to the 'Use on the web' section in the drawer. Then, copy the @import inside of the style tag. Copy this code on the top of your styles.css file.
Now you have imported the font. To include it in the project (and for practical usage) this font could be applied to the body tag.
To set the font, go to the 'CSS rules to specify families' section in the drawer, copy the rule, and then paste it into the selector that you use for styling the body tag.