Wie verwende ich das Paket stix2-otf

luaotfload | db : Reload initiated (formats: otf,ttf,ttc); reason: Font "STIXTwo
Text" not found.

! Package fontspec Error: 
(fontspec)                The font "STIXTwoText" cannot be found; this may
(fontspec)                be but usually is not a fontspec bug. Either there
(fontspec)                is a typo in the font name/file, the font is not
(fontspec)                installed (correctly), or there is a bug in the
(fontspec)                underlying font loading engine (XeTeX/luaotfload).

For immediate help type H <return>.
 ...

l.19 \setmathfont
                 {STIXTwoMath}

A font might not be found for many reasons.
 Check the spelling, where the font is installed etc. etc.

 When in doubt, ask someone for help!


luaotfload | aux : no font with id 0
luaotfload | aux : no font with id 0

Package fontspec Info: 
(fontspec)             Could not resolve font "STIXTwoText/BI" (it probably
(fontspec)             doesn't exist).


Package fontspec Info: 
(fontspec)             Could not resolve font "STIXTwoText/B" (it probably
(fontspec)             doesn't exist).


Package fontspec Info: 
(fontspec)             Could not resolve font "STIXTwoText/I" (it probably
(fontspec)             doesn't exist).


! Package fontspec Error: 
(fontspec)                The font "STIXTwoText" cannot be found; this may
(fontspec)                be but usually is not a fontspec bug. Either there
(fontspec)                is a typo in the font name/file, the font is not
(fontspec)                installed (correctly), or there is a bug in the
(fontspec)                underlying font loading engine (XeTeX/luaotfload).

For immediate help type H <return>.
 ...

l.19 \setmathfont
                 {STIXTwoMath}

A font might not be found for many reasons.
 Check the spelling, where the font is installed etc. etc.

 When in doubt, ask someone for help!

%!TeX LuaLaTeX
\documentclass{scrartcl}

%\usepackage{stix2}
\usepackage[
    math-style=ISO,
]{unicode-math}

\setmainfont{STIXTwoText}
\setmathfont{STIXTwoMath}

\begin{document}
Hallo Welt, \(a+b=c^2\).
\end{document}