When to use "Et"

Norwegian 4:

“han skal dra på museumet i ettermiddag” meaning “he’s going to go to a museum this afternoon.”
“Museumet” means “the museum,” yet this sentence clearly says: “He is going to a museum.” Should it not be translated as: “Han skal dra pa et museum?”

That’s right, the English translation is wrong.
But the Norwegian is also wrong. “Museumet” is incorrect spelling. If you type it with a Norwegian dictionary setting, it will get red-lined.
The correct spelling in the definite form is “museet” (pronounced “musé-e”)