Only skimmed the thread but if you have water coming in under the door then getting stuck in the debris there + under a carpet I'd try clearing out under the door and removing the carpet. That way you get the airflow going and it has a chance to dry out in between rains. A de-humidifier will help massively with this.
Looks like you need to re-do that concrete slab anyway, but that looks like a mission
Only skimmed the thread but if you have water coming in under the door then getting stuck in the debris there + under a carpet I'd try clearing out under the door and removing the carpet. That way you get the airflow going and it has a chance to dry out in between rains. A de-humidifier will help massively with this.
Looks like you need to re-do that concrete slab anyway, but that looks like a mission