Are you using a custom skin? as far as I can tell it's saying it cannot find ADM_CONTENT in this file
https://github.com/ILIAS-eLearning/ILIAS/blob/release_5-4/Modules/Test/templates/default/tpl.il_as_tst_kiosk_mode_content.html#L4
Are you overriding this template in a skin potentially?
https://github.com/ILIAS-eLearning/ILIAS/blob/release_5-4/Modules/Test/templates/default/tpl.il_as_tst_kiosk_mode_content.html#L4
Are you overriding this template in a skin potentially?