El dibujante llega a la firma de autores.

Not necessarily. Dibujante is a noun with the same form for both male and female people. The article tells you the gender here:

• el dibujante = a male illustrator / the male illustrator
• la dibujante = a female illustrator / the female illustrator

So the word itself does not change, but the article usually does.

El is the masculine singular definite article, meaning the. It shows that we are talking about a specific illustrator, not just any illustrator.

Compare:

• El dibujante = the illustrator
• Un dibujante = an illustrator

So el makes the noun definite and specific.

In Spanish, llegar often takes a before the place or event someone arrives at.

• llegar a casa = to arrive home
• llegar al colegio = to arrive at school
• llegar a la firma = to arrive at the signing event

If you do not mention the destination, you can simply say llega on its own. But once the destination is included, a is normally used.

Because al is only the contraction of a + el.

• a + el = al
• a + la = a la

Since firma is a feminine noun, it uses la, so the correct form is a la firma.

Here firma does not just mean a written signature. It can also refer to a signing event or signing session. So la firma de autores means something like the author signing event or the signing session with authors.

In Spain, especially in book fairs, comic conventions, and similar events, this kind of expression is common. Depending on the context, you might also hear:

• firma de libros
• sesión de firmas
• simply firmas

Here de autores describes the type of event. It means something like an authors' signing event or a signing event involving authors. It is a general classifying phrase, so Spanish often leaves out the article.

Compare:

• firma de autores = an authors' signing event, the type of event
• firma de los autores = the signing session of the authors, referring to specific authors already identified

So without los, the phrase sounds more like the name or category of the event.

The present tense in Spanish can be used in several ways. Here llega could mean:

• arrives
• is arriving
• sometimes even a narrative arrives in a description of events

Spanish often uses the simple present where English might prefer either the simple present or the present continuous, depending on context. So llega is completely normal here.

In Spanish, autor can be broader than the English word author. It often refers to a creator, not only a writer of text. In comics, graphic novels, and illustrated works, a dibujante may also be considered one of the autores of the work.

So in this kind of context, autores can naturally include writers, illustrators, or other creators involved in the work.