Open Font Book and the folder with the bundle of fonts that you would like to install. Make sure to only open the OTF or TTF files.
If your fonts are spread across different folders, use the search functionality at the upper right corner of the window to search for .ttf or .otf files only.
Mark the fonts that you want to install.
Drag and drop the marked fonts into Font Book. The fonts will now start installing on your computer.
You might get an error message while installing the fonts. No worries, you can simply tick Select all above and click Installed Check to continue. We’ve explained why this error occurs here (Link to tutorial Error message while installing on Mac).
When the installation is done, make sure to restart your application. If that doesn’t work restart your computer. You can now go ahead and use your new fonts!