The chemical formula is not NaO2.Al2O3.2SiO2.9/2H2O but it is Na2O.Al2O3*2SiO2*9/2H2O and which indicates a strongly basic, co-crystalline compound due to the presence of Na2O.
However, molecular sieves are moderately basic and thus, the stoichiometric formula Na12Al12Si12O48·27H2O (zeolite type A) is more successful as indicating hydrate co-crystals of sodium silicate and sodium aluminate that are basic after hydrolysis.
The confusion about acidity starts from the amphoteric nature of Al2O3 (if adopting the mixed oxides formula) that may produce salts with both acids (e.g. AlCl3) and bases (e.g. Na2Al2O4). Anyway, molecular sieves are basic and not acidic.
But although molecular sieves are moderately basic in water, their basicity increases in organic solvents and thus, they are not compatible with strong acids, aliphatic halides (E2 elimination), etc.