La kandidato atendas la laborintervjuon.

Because Esperanto atendi normally takes a direct object.
English says wait for the job interview, but Esperanto says literally wait the job interview:

La kandidato atendas la laborintervjuon.

So you do not add a separate word meaning for here. The object is shown by the accusative -n on laborintervjuon.

The -n marks the direct object, the thing being awaited.

• La kandidato = the candidate, the subject
• atendas = waits for / is awaiting
• la laborintervjuon = the job interview, the object

So -n helps show who is doing the action and what receives the action.

These are very basic Esperanto endings:

• -o = noun
  
  • kandidato = candidate
  • laborintervjuo = job interview
• -as = present tense verb
  
  • atendas = waits / is waiting / awaits
• -n = accusative ending, usually marking the direct object
  
  • laborintervjuon = the job interview as object

So -on is really -o + -n.

Because both nouns are definite in this sentence:

• La kandidato = the candidate
• la laborintervjuon = the job interview

In Esperanto, la is the only article, and it means the.
Unlike English, Esperanto has no separate word for a/an.

Also, la never changes. It stays la whether the noun is singular, plural, subject, or object.

Yes, if you do not mean a specific, known interview.

• La kandidato atendas la laborintervjuon = the candidate is waiting for the job interview
• La kandidato atendas laborintervjuon = the candidate is waiting for a job interview / job interview(s), depending on context

Since Esperanto has no a/an, a bare noun often covers that meaning.

No. Atendi can also mean expect.

For example:

• Mi atendas la buson. = I am waiting for the bus.
• Mi atendas bonajn rezultojn. = I expect good results.

So context decides the best English translation. In your sentence, the meaning shown to the learner tells you which one is intended.

Because Esperanto very commonly forms compound words.

Here:

• labor- = work / job
• intervjuo = interview

Together: laborintervjuo = job interview

This is very normal in Esperanto. Usually the last part is the main noun, and the earlier part modifies it.

You might be understood, but laborintervjuo is the more natural way to say job interview.

A compound like laborintervjuo names a specific type of interview.
A phrase like labora intervjuo sounds more like work-related interview, which is less idiomatic for this idea.

So for job interview, the compound is the safer choice.

Yes, Esperanto word order is somewhat flexible because the accusative -n shows the object.

The most neutral order is:

La kandidato atendas la laborintervjuon.

But you could also say:

La laborintervjuon atendas la kandidato.

That is grammatical, but it sounds more marked or emphatic. In normal everyday use, the original subject-verb-object order is the most natural.

No. In normal Esperanto, kandidato is gender-neutral unless context says otherwise.

• kandidato = candidate
• kandidatino = female candidate
• virkandidato = male candidate, if you really need to specify

So La kandidato does not automatically mean a man.