calibre-web kobo synch

My English isn’t good, so I’ll use google to translate it!
I have installed the image in Docker on my “Synology”, but if I want to download a book on my Kobo, it doesn’t work, what can be wrong? I synced Kobo, created a shelf, pushed books onto the shelf! The shelf with the books is displayed on the Kobo, but you can’t download them?!