Keep getting "Excel ran out of resources while attempting to calculate one or more formulas."

I suggest to replace all references to entire columns with actual cell addresses including the row numbers. Your data seems to span one year so you can replace $A:$A with $A$2:$A$367 in all your elaborate COUNTIFS formulas.
NB: Please check the formula in cell Q5 on the Courses sheet, it is different from the ones above it and below it.