Is working now i think. Vlad has updated marketplace client, which will be released shortly. What were your issues?
Discussion
My problem is that I can't use "Nostr market" because "Nostr client" I don't have permission to use it...
I've tried using Marketplace extension, but I don't like how it handles images and it doesn't integrate directly with Nostr.

You should run lnbits yourself if you want to control the client extension. The Nostrclient extension can only be managed by the admin of the server as they can decide what relays the extension should connect to. Your shop seems to work fine for me

After writing to you I tried the Nostrmarket again and even without the Nostrclient extension it seems to work:
This is my paintings showcase on Zapit Marketplace extension, but it's not good to showcase the paintings or easily manage the sale, see for yourself: