FECYT's website publishes the "Research career path in Spain", which includes a detailed description on research funding opportunities at all career stages (and links where to find further info).
Currently there are no openings in the group. However, many postdoctoral researchers come to Barcelona with their own funding. This includes competetive grants like Marie Skłodowska-Curie Fellowship (EU), Juan de la Cierva (Spain), Beatriu de Pinós (Catalunia), INPhINIT (La Caixa), and EUTOPIA-SIF.