ᐅ Waterproofing insulation in the terrace area with a bitumen-based coating

Hello Forum,

I have the following question:

We are currently installing our terrace. At the door area, the insulation was cut out by the developer. What is the best way to seal this now? I have often been advised to use bitumen. However, no specific product was mentioned. The coatings I found all say "Not suitable for plastics." Can you advise me on the best approach?

I also have bitumen filler from Plasticol. Would that be usable?