Neither of them is right or wrong, really. "Volk" can have very specific connotations in German (e.g. "völkisch" nationalism is similar to ethno-nationalism but

Neither of them is right or wrong, really. "Volk" can have very specific connotations in German (e.g. "völkisch" nationalism is similar to ethno-nationalism but the concepts of "Volk" and ethnic group are not entirely identical which is why a separate term exists for the concept and why the English term uses it as a loanword). "Folk" can mean many different things in English. There is no exact overlap between words across languages most of the time so it depends on the context. For example, while "Leute" in German also translates to "people", in "power from the people" that word would be correctly translated as "Volk" not "Leute" as it refers to the people as an abstract political force from which a state's power is derived.