Pergola awning post installation on walkway slabs

Hello everyone
We would like to replace our awning, which is located on the rooftop terrace. The orientation is westward.
We have received an offer (just under 19,000 CHF) for a pergola awning combined with a vertical awning.
The awning installer wants to secure it using flower boxes measuring 50x50x50cm (150kg). Two pieces are needed for this.
However, these take up a lot of space.

Questions:
We have come across the Sowol pergola awning.
The posts are attached using floor flanges.
Is it possible to mount the posts on the paving slabs? These lie on gravel. Flower boxes are also placed on the paving slabs, see photo.
The awning will still be fixed during installation.
We would rather not drill into the roof to attach the mounting flanges.

Many thanks for your help.

Best regards, Sandro

We are currently facing the same problem (although no roof terrace). I was already aware that fastening on the terrace slabs is not possible. However, my hope was that the curb stones, which do indeed have a great foundation, could be used. I had planned a metal shoe that I could slip over the curb stones. But I was enlightened otherwise by two different awning builders. Unfortunately, I cannot avoid a proper foundation. Therefore, I think the suggestion with the two flower boxes will be the only solution for you.

The existing awning looks quite high-quality. Why should it be removed? Wouldn't re-covering it help?