If you want to avoid using pivot tables, you have a few options. The path I'd take would be to use hidden calculated fields to summarize your data.
For example, on your Sales table, insert a 'Month' column that calculates the "MM/YY" value for any given date using the formula:
=DATE(YEAR($A2),MONTH($A2),1)
this will calculate the first day of the month specified in column A.
I chose to format this cell to show 'January 2024' (e.g. omitting the day number, but that's not critical)
You can hide this column so you don't have to see it (or accidentally edit it).
Then on your Summary sheet, you use SUMIF() statements to compare the date in Summary::Monthly::A to the (hidden) column on the Sales table:
=SUMIF(Sales::Sales Data::Month, $A2, Sales::Sales Data::Total Sales)
This tells numbers to look in the (hidden) 'Month' column on the Sales Data sheet and check the values against $A2 on the Summary sheet. For every match it adds the corresponding value from the Total Sales column.
You can use this to summarize any of the data from the other columns, too.
Repeat the exercise for the Quarterly Table, using a (hidden) column on either the Sales Data or the Monthly table that calculates the corresponding Quarter.