Learn Swedish: Men du får inte glömma passerkortet hemma. - But you must not forget the access card at home.

This is a common trap! In Swedish, får inte means "must not" or "may not" (expressing a strict prohibition). If you want to say "do not have to" (meaning the action is optional), you use behöver inte. Since leaving the card behind is forbidden here, får inte is the correct choice.

Why is the verb glömma used without att here?

Får is a modal verb, which means it works like "can" or "must" in English. In Swedish, modal verbs are always followed directly by the bare infinitive of the next verb. Therefore, we use glömma without the infinitive marker att.

Why does the sentence use hemma instead of hem?

Hemma indicates a fixed location ("at home"), while hem indicates motion towards a destination ("homewards" or "to home"). Even though you might think of forgetting as an action, the card itself stays in a static location at your house, so the location word hemma is required.

How is the word passerkortet built?

It is a compound noun made from the verb passera (to pass) and the noun kort (card). The -et at the very end is the definite suffix for an ett-word, which changes the meaning from "an access card" to "the access card".