The Polish government licensed the right to build several Fiat cars under the brand “Polski Fiat”. Fiat was pretty open to doing a deal with communist states if they could, and communist states were more than happy to be “inspired” by other manufacturers when designing cars, either by stealing ideas (Trabant 600 has lots of ideas taken from VW and Saab cars of the era), or through proper licensing deals. The first Lada for example is a Soviet government take on the Fiat 126p.

That doesn't mean all that much though, there were several Fiat cats being built in eastern/southern Europe.

E.g. Zastava was building them (the Yugo, "crappiest" car in the world was a licensed Fiat platform, same with 101 and 750). Polski Fiat was another example of Fiats common licensing of their platforms to Eastern Europe.

They weren't very good, but they were available.

Communist Poland eas manufacturing Fiats on a licence.

They were building Fiat's in license all over the former Soviet countries.

They were so rare every second car in Poland was a Polski Fiat when the war fell. The other big brands in Poland were Polonez, Serena, some Wartburgs, the occasional Zil and lots of Skoda's as well. Some so old that they'd have been in a museum on the other side of the wall but doing daily service in the East.

Fiat was very popular in Poland and was also manufactured in Poland.

Fiat 126p or 125p was a staple of communism in Poland.