Using the online installer from https://www.qt.io is the easiest approach, though it may be possible to install through your system's package manager (if you want to try the package manager approach, then first read the Qt Linux documentation at https://github.com/therecipe/qt/wiki/Installation-on-Linux). On most Linux platforms, the Qt downloads website will correctly detect the platform and offer a simple run installer. After downloading the file, you should make it executable and then run it:

This will start the installer just as on macOS; from here, follow the onscreen instructions and complete the installation.