Welcome to the forum.

The today function will give today's date. The weekday function will return the day of the week, I will use weekday(today(),16) to return day of the week as numbers 1 (Saturday) to 7 (Friday).

You should be able to combine these to get the last Saturday as follows:

Formula: copy to clipboard
=TODAY()+WEEKDAY(TODAY(),16)-1


(this will give today's date if today is a Saturday)

You can then add or subtract as many sets of 7 days as you like to find future or past Saturdays.

I.e. Assuming above formula is in cell A1, next Saturday is calculated as:

Formula: copy to clipboard
=A1+7


Hope this helps (and works!)