I’m with VDC on this. Typically these creaks are the result of drying, cracking, shrinking rubber bushings.
One particular bushing that I’ve found commonly does this on cars the age of yours is the bushing that holds the antisway bar to the chassis. The bar turns in the rubber bushing every time the wheel goes up & down, and it wears the hole to a larger size. It can be quieted temporarily with a bit of lubricant of just about any kind, but it’ll ultimately have to be changed.
Other bushings are possibilities too, and as VDC said it could be something more serious, but hopefully this idea will help lead to the squeak.
As regards the springs, I suspect he was alluding to the places where the spring ends are held captive by the strut components. As you can see from the attached “exploded view” drawing of my own components, there’s typically an “insulator” or a pad at each end of the apring to soak up vibrations. Perhaps that’s whata your guy was referring to.