Hi @Banjo1959,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
The installation of a concertina door such as this Pillar 82 x 203cm White Monaco PVC Concertina Door is done with a series of brackets, screws and a top track that is proprietary to their door system.
Unfortunately, I'm not aware of a concertina door that would fit this size, so it is likely modifications would need to be made to the opening, or a custom-made door would be required.
I'd suggest contacting a carpenter that specialises in doors to assist you with this project.
Jacob
