“How do I install a font I’ve downloaded onto my Mac laptop running OS X?”
Install Fonts on a Mac:
All Mac’s running OS X v10.3 and later come with a little handy application called Font Book. Font Book lets you view, organize, install and remove fonts easily on your Mac computer.
To install a downloaded font simply click on the font from your Mac. Font Book should open by default.
A preview pane will open displaying the font. To install the font onto your Mac hit the ‘Install Font’ button.
To intall multiple fonts I recommend opening Font Book and going to File -> Add Fonts. Find the fonts on your computer. Hold the Command key and select each font. Click ‘Open’ to install all the selected fonts onto the Mac.
If you want to manually install fonts check out this Apple support guide.