Salzburg PRO is translation ready, just place your theme language files in /languages folder. Alternatively, you can use Loco Translate plugin that provides in-browser editing for WordPress translation files.
Please visit the following links to learn more about translating WordPress themes:
https://make.wordpress.org/polyglots/teams/
https://developer.wordpress.org/themes/functionality/localization/
https://developer.wordpress.org/reference/functions/load_theme_textdomain/