Quiver plot with each with 5km*5km box having single quiver arrow average of all arrows within the box

I have U wind, V wind, X (lon) and Y (lat) column matrices each of size (7581*1) X and Y ranges from -125 to 125 (converted lat lon to xy w.r.t centre 0). So with 5km square box we have 50*50 boxes total

I wish 50*50 quivers instead of all 8000 quivers for each X and Y. Instead I wish to plot 1 averaged quiver for a given box of 5km by 5km resolution

I have attempted a code but somehow it doesnt work. I am attaching the code for your perusal. I use 1012a version

Any help will be appreciated a lot!