Because of the coronavirus, the Polish government introduced nationwide special precautionary measures. From Friday the 13th until at least April 26 all institutions, cultural venues like cinemas, museums and theatres, across all of Poland. So all Kraków's tourist attractions and cultural institutions will be closed until at least April 26. Read more about coronavirus in Krakow
Yes, the entrance to the Museum is free of charge and you can visit Auschwitz on your own. It does not refers to the period between April 1st and October 31st, when the entry is possible only for guided tours.