Zotero import : Error when requesting Zotero library: Forbidden

HI,

I am trying to import my group library Zotero in Omeka-S and here is the essage I get : Error when requesting Zotero library: Forbidden. Does anyone know where it could come from ? I am used to import my library without any problem so I am quite surprised of this error message. I precise I am the owner of the group library, so I guess I have the rights to down load it on Omeka-S. Many thanks I you have some tips to help me.
Have a nice day,
Emilie