iyonggwone ttara churip kadeuga piryohaeyo.

-에 따라 means depending on, according to, or based on.

So 이용권에 따라 출입 카드가 필요해요 means that whether you need an access card changes depending on the type of pass/ticket.

A few similar examples:

• 상황에 따라 달라요. = It depends on the situation.
• 날씨에 따라 일정이 바뀔 수 있어요. = The schedule may change depending on the weather.

이용권 is a noun meaning a pass, ticket, or voucher for use.

It is often used for things like:

• gym passes
• sauna passes
• amusement park passes
• facility use tickets

It is broader than just a transportation ticket. In this sentence, it refers to some kind of pass for using a facility or service.

Because 따라 here is not the verb to follow something physically. It is part of the expression N에 따라, which means according to / depending on N.

Compare:

• 선생님을 따라 갔어요.
  = I followed the teacher.
  Here, 따르다 is a normal verb, so it takes 을/를.

• 규칙에 따라 해야 해요.
  = You have to do it according to the rules.
  Here, 에 따라 is a grammar pattern.

So in your sentence, 이용권에 따라 is the fixed pattern meaning depending on the pass.

Because 필요하다 works more like to be necessary than to need.

In Korean, the thing that is necessary usually takes 이/가:

• 물이 필요해요. = Water is necessary. / I need water.
• 시간이 필요해요. = Time is necessary. / I need time.
• 출입 카드가 필요해요. = An access card is necessary.

English uses need as a verb with a direct object, but Korean usually expresses this idea with 필요하다, an adjective-like word.

So:

• natural: 출입 카드가 필요해요
• unnatural: 출입 카드를 필요해요

출입 means entering and exiting or access.
카드 means card.

So 출입 카드 means an access card, entry card, or card used to enter a place.

You may also see related words like:

• 출입문 = entrance/exit door
• 출입증 = access badge, ID pass
• 출입하다 = to enter and leave / come and go

In this sentence, 출입 카드 is the card needed to access the place.

Korean often leaves out the topic marker when it is not needed.

This sentence focuses on the fact that an access card is necessary depending on the pass, so 출입 카드가 marks the thing that is necessary.

You could say:

• 이용권에 따라 출입 카드가 필요해요.

If you added 은/는, the nuance could change slightly:

• 출입 카드는 이용권에 따라 필요해요.

That version is possible, but it sounds a little more like you are specifically talking about the access card as the topic. The original is more natural in many everyday situations.

Grammatically, 필요하다 is usually treated as a descriptive verb (often called an adjective in Korean learning materials).

That is why it behaves differently from an action verb like 먹다 or 가다.

For example:

• 필요해요 = is necessary / need
• 필요했어요 = was necessary / needed
• 필요하면 = if it is necessary / if you need it

Even though it is translated as need in English, its Korean structure is closer to be necessary.

Yes, but depending on the pass is usually more natural in this sentence.

Both are possible:

• Depending on the pass, an access card is required.
• According to the pass, an access card is required.

However, according to can sound a bit more formal or rule-based in English. Since the meaning is that the requirement changes by pass type, depending on is often the best translation.

필요해요 is in the 해요체, the standard polite style.

It is polite and very common in everyday speech.

Related forms:

• 필요합니다 = more formal
• 필요해 = casual/informal
• 필요해요 = polite everyday speech

So this sentence is appropriate for normal polite conversation, announcements, or staff speaking politely to customers.

Yes. 에 따라 and 에 따라서 are both used.

• 이용권에 따라 출입 카드가 필요해요
• 이용권에 따라서 출입 카드가 필요해요

The version with -서 can sound a little fuller or slightly more formal in some contexts, but the meaning is essentially the same here.

In Korean, nouns often appear without articles, so 출입 카드가 필요해요 could mean:

• an access card is needed
• the access card is needed
• access cards are required

The exact meaning depends on context.

In most practical contexts, this sentence means something like:

• You need an access card depending on your pass type or
• An access card may be required depending on the pass

So Korean leaves this more open than English does.

Yes, Korean word order is flexible as long as the particles make the roles clear.

Original:

• 이용권에 따라 출입 카드가 필요해요.

Possible variation:

• 출입 카드가 이용권에 따라 필요해요.

Both are understandable, but the original sounds more natural because 이용권에 따라 sets up the condition first: depending on the pass.

That order is very common in Korean:

1. condition/background
2. main statement

A close breakdown is:

• 이용권에 따라 = depending on the pass
• 출입 카드가 = an access card
• 필요해요 = is necessary

So very literally:

• Depending on the pass, an access card is necessary.

That literal structure helps explain why Korean uses 가 필요해요 instead of the English-style need + object.