Hi Vincent,
thank you for your kind reply.
Quixel library has now started working. The problems I've encountered are with creating the object and with creating the variations of the 3D objects.
From archicad, in addition to the direct link not working, I can't save the file in datasmith format and when I try to do the software crashes. So I can't follow the procedure you indicated, and I can only tell you which plugin version is installed. I recently downloaded it and it is the "DatasmithARCHICAD26Exporter.bundle" dated October 21, 2022.
At the moment I work by exporting .skp files, but sometimes twinmotion doesn't load any extensions.
Thanks for your attention.
Giorgio