the setup process w/ 1.5.3-maintenance fails due to a replaced link for codemirror.
see:
Version 6 is the current version and Version 5 was placed in a subfolder /5
https://codemirror.net/5/codemirror-5.21.0.zip
could you please adjust to the new url:
https://github.com/i-MSCP/roun…roundcubemail/jsdeps.json
or allow curl to follow redirects in install-jsdeps.sh: