Word order in Polish is not fixed like in English
But there are ways of saying things that are more correct than others.
For one summer barbeque at work, we had a big green flowerpot (about 1500 litres) filled with cold water to keep the bottles of beer cool in the tropical English sunshine. A Polish workmate insisted that it was a "green big pot". I can see the logic of putting the adjectives in such an order, but for a language with supposedly free(ish) word order, things do seem to be a little more set than descriptions of the Polish language would suggest.
English word order is "fixed" in that the order of words has a grammatical function. That doesn't mean there aren't different ways of ordering words in a sentence without changing the meaning even slightly. (Admittedly, certain words have to be added or dropped to make a change in word order work - the English equivalent to the Polish dative case being an example. "I give the donkey some grass" / "I give some grass
to the donkey.")
"Ona mi pozwala" versus "Pozwala mi" or "Ona pozwala" vary in that of whom is being spoken may or may not need to be mentioned, but if one were to say "Ona pozwala mi" rather than "Ona mi pozwala", would it sound slightly awkward or less correct, or would it just be a change in nuance?