Can't start Aseba Studio on Ubuntu

[mr-who2012]

I freshly installed the flatpak on ubuntu and can't launch the simulator. When starting the program, the console-output reads some permission-errors:

flatpak run org.mobsya.ThymioSuite
QtWebEngine::initialize() called with QCoreApplication object already created and should be call before. This is depreciated and may fail in the future.
Attribute Qt::AA_ShareOpenGLContexts must be set before QCoreApplication is created.
Searching for  "thymio-device-manager"
"thymio-device-manager" found:  "/app/bin/thymio-device-manager"
thymio-device-manager starting
[2023-04-13 02:36:32.794] [console] [info]             main.cpp@L105:   Starting...
[2023-04-13 02:36:32.794] [console] [error]             main.cpp@L178:  Exception thrown: Permission denied
"de_DE" "launcher_" ":/translations"
"de_DE" "qtdeclarative_" "/usr/translations"
"de_DE" "qtbase_" "/usr/translations"
"de_DE" "qtwebengine_" "/usr/translations"
qrc:/qml/SettingsMenu.qml:149:21: QML QQuickItem: Bei einem vertikalen Anker wurde eine potentielle Endlosschleife der Anker festgestellt.
qrc:/qml/SettingsMenu.qml:149:21: QML QQuickItem: Bei einem vertikalen Anker wurde eine potentielle Endlosschleife der Anker festgestellt.
Searching for  "asebaplayground"
"asebaplayground" found:  "/app/bin/asebaplayground"
qrc:/qml/SettingsMenu.qml:149:21: QML QQuickItem: Bei einem vertikalen Anker wurde eine potentielle Endlosschleife der Anker festgestellt.
qrc:/qml/SettingsMenu.qml:149:21: QML QQuickItem: Bei einem vertikalen Anker wurde eine potentielle Endlosschleife der Anker festgestellt.
thymio-device-manager started
thymio-device-manager stopped
thymio-device-manager stopped with exit code 1
"Verbindung verweigert"

Afterwards, I click on "Aseba Studio", then on "start a simulation" and choose my file in the file-browser. For a second, an empty window pops up, vanishes and the console reads:

Searching for  "asebaplayground"
"asebaplayground" found:  "/app/bin/asebaplayground"
qrc:/qml/ThymioSelectionView.qml:85: TypeError: Cannot read property 'icon' of undefined
qrc:/qml/ThymioSelectionView.qml:93: TypeError: Cannot read property 'name' of undefined
qrc:/qml/ThymioSelectionView.qml:154: TypeError: Cannot read property 'descriptionImage' of undefined
qrc:/qml/ThymioSelectionView.qml:185: TypeError: Cannot read property 'descriptionTextFile' of undefined
qrc:/qml/ThymioSelectionView.qml:67: TypeError: Cannot read property 'supportsWatchMode' of undefined
qml: studio
Searching for  "asebaplayground"
"asebaplayground" found:  "/app/bin/asebaplayground"
Could not load ground texture file named "logo_thymio_couleur_fond.png"
/usr/include/c++/10.2.0/valarray:594: _Tp& std::valarray<_Tp>::operator[](std::size_t) [with _Tp = double; std::size_t = long unsigned int]: Assertion '__builtin_expect(__i < this->size(), true)' failed.

That's it. I can't start the simulation. Any help appreciated.