module "org.kde.kirigami" and "org.kde.desktop" not installed (On Fedora and ArchLinux)

I'm following the tutorial: A full Python + Kirigami application to learn how to build Python applications using PySide6 and Kirigami for KDE, under Arch Linux and Fedora. However, when running the script, I get the following error:

import QtQuick
import QtQuick.Layouts
import QtQuick.Controls as Controls
import org.kde.kirigami as Kirigami

Kirigami.ApplicationWindow {
    id: root

    title: qsTr("Simple Markdown viewer")

    minimumWidth: Kirigami.Units.gridUnit * 20
    minimumHeight: Kirigami.Units.gridUnit * 20
    width: minimumWidth
    height: minimumHeight

    pageStack.initialPage: initPage

    Component {
        id: initPage

        Kirigami.Page {
            title: qsTr("Markdown Viewer")

            ColumnLayout {
                anchors {
                    top: parent.top
                    left: parent.left
                    right: parent.right
                }
                Controls.TextArea {
                    id: sourceArea

                    placeholderText: qsTr("Write some Markdown code here")
                    wrapMode: Text.WrapAnywhere
                    Layout.fillWidth: true
                    Layout.minimumHeight: Kirigami.Units.gridUnit * 5 
                }

                RowLayout {
                    Layout.fillWidth: true

                    Controls.Button {
                        text: qsTr("Format")
                        onClicked: formattedText.text = sourceArea.text
                    }

                    Controls.Button {
                        text: qsTr("Clear")
                        onClicked: {
                            sourceArea.text = ""
                            formattedText.text = ""
                        }
                    }
                }

                Text {
                    id: formattedText

                    textFormat: Text.RichText
                    wrapMode: Text.WordWrap
                    text: sourceArea.text

                    Layout.fillWidth: true
                    Layout.minimumHeight: Kirigami.Units.gridUnit * 5
                }
            }
        }
    }
}
I run it with: python3 src/__main__.py And I get this output:

./src/qml/main.qml:4:1: module "org.kde.kirigami" is not installed ./src/qml/main.qml: module "org.kde.desktop" is not installed My problem: I can’t figure out how to fix the error: module "org.kde.kirigami" and "org.kde.desktop" is not installed But Kirigami is already installed on my system.