Did you unzip the font folder you downloaded and then right click on the font file and press “Install”? As soon as you hit install, it should automatically pop up in the font list in your editing program. If you’ve installed it and it’s not showing up, you may have to restart your editing program if you had it open during the installation process.
Here are screenshots showing what to do to install a new font using Windows:
After you download your zipped font, right click on it and click “Extract to____”:
Next, open the newly created folder and right click on the font file and click “Install”:
If you need anymore help, let me know! :)