The A foundation was the organizer of/for this meeting.
少し意訳になりますが
1) This meeting was organized by the A foundation.
「この会議はA財団主催で行われた」
2) The A foundation was the organizer of/for this meeting.
「A財団がこの会議の主催者です
世話役・世話人・主催者：organizer
財団・財団法人：foundation
日本 
