Apparently, there is a plugin called Processing tools or Processing which QuickOSM needs.
I was advised to make sure the Processing plugin is activated (checked) which I did and the QuickOSM tool ran successfully.
All this seems to be largely undocumented except for this discussion at https://gis.stackexchange.com/questions/470909/error-in-quickosm-panel-im-unable-to-access-osm-data
Anyway, I have got it to work which is good.
Cheers
Dr Iain Stuart
JCIS Consultants
President Royal Australian Historical Society
P.O. Box 2397
Burwood North
NSW, 2134
(02) 9701 0191
(0413) 380116 (m)