When using any application that allows us to write texts, we must first take into account, the sources we have available. Fonts are an external element that is associated with documents that allows us to save certain information independently, such as Photoshop files in PSD format, Pixelmator files or, without going any further, Microsoft Word, Pages and the rest. The main reason for not including the font in the document is the final space that the document could occupy.
The same happens with web pages. A few years ago, many different fonts were used to create attractive web pages, but did not take into account the font used, which did not have to be downloaded independently, not being available natively on the system. If the corresponding font was not downloaded, the browser made use of the system's default font, offering a result that was far removed from the reality that the web designers had created.
When installing a new font in macOS, as in the latest versions of Windows, the process is extremely simple and it does not require that we navigate through the system directories looking for the location where we should copy it. Once we have downloaded the font in question, we just have to double click on it.
Below is will show us a confirmation message to allow that the font is installed on our Mac, we just have to click on accept and that's it. At that moment we can go to the application where we want to use the new font and search for it among the available fonts.
You must bear in mind that if you want to share the result in PSD, WORD or any other format that requires the original source, you must include it together with the file. If you only want to share the result the result, you just have to create a file in JPG format, a format that does not require the source independently.