Polyglossia; Arabic font found

Question

I have TeX Live 2017 installed on a macOS Sierra.

I get an error when I compile this simple document.

%% XeLaTeX
\documentclass{article}

\usepackage{polyglossia}

\setmainlanguage{english}
\setotherlanguage{arabic}

% Setting a font
\newfontfamily\arabicfont[Script=Arabic]{Amiri}

\begin{document}

Hello, and this is an Arabic Hello \textarabic{ﻡﺮﺤﺑﺍ}


\end{document}

The Error;

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
! fontspec error: "font-not-found"
! 
! The font "Amiri" cannot be found.
! 
! See the fontspec documentation for further information.
! 
! For immediate help type H <return>.
!...............................................  

l.8 ...fontfamily\arabicfont[Script=Arabic]{Amiri}

? 

How can I install fonts in Polyglossia?

Answer 1

XeLaTeX uses system fonts, so, if you don't have Amiri on your computer, then you need to download it and put it into your computer's font folder.

Also, shouldn't it be مرحبا, not ﻡﺮﺤﺑﺍ?