Does GEE compute mean values of AODs with this code -or this is the erroneous part in the code?

Question

EDIT: I updated the code at Getting data to Drive or Cloud from GEE?

My initial concern was as written below:

What is wrong with the code below, if any?

My aim is to get the mean daily Aerosol Optical Depth (AOD) values from MODIS MAIAC AOD data (I took this code from the question given at Download daily mean AOD data GEE posted by an author, thanks, but there seems to be no way to contact, plus there may be additional valuable suggestions from any of you)

Afterwards, I want to export the mean AOD values list to Drive or somewhere.

I assume that "AOD.map" in the code comes from MODIS AOD data and that I do not need to define it as "var". I cannot find anything like ".map" when I search in GEE. I could not figure out this. EDIT: OK now I see it when I search for function(f) or function(img) but still cannot understand what is wrong with the code.

I also posted an associated request for help at Getting data to Drive or Cloud from GEE? , thinking that the problem with the code was actually only at the stage of exporting the data, but maybe GEE is not able to make the computation of mean values in the first place, which is the reason of this post. Btw, that other question received no answers.

var AODmeanF = AOD.map(function(img) {

  return img.reduceRegions({

    collection: FeatureF,
    reducer: ee.Reducer.mean(),
    scale: 1000,
  }).map(function(f) {

    return f.set('date', img.date());
  });
}).flatten();

PS: All I define among these variables is "FeatureF" (as a rectangular area).