Learn French: Je suis ravi que mon ami ait décroché ce poste. - I am thrilled that my friend landed this job.

The phrase Je suis ravi que expresses an emotion, which requires the subjunctive. We use the past subjunctive (ait décroché) because the action of landing the job happened before your current feeling of being thrilled. This shows anteriority, meaning it is a past event relative to the main verb.

Is it possible to use the passé composé (a décroché) here since it is an undeniable fact that he got the job?

No, you must use the subjunctive. Even when the event is a fully confirmed fact, expressions of emotion like être ravi que strictly trigger the subjunctive. In French, the subjunctive is not only for doubt; it is also used to frame facts through a lens of personal emotion or judgment.

I usually see décrocher translated as 'to pick up the phone'. How does it mean 'landed' in this sentence?

Literally, décrocher means 'to unhook.' In everyday French, it is commonly used figuratively to mean obtaining something competitive or hard-earned. You will often hear it used with things like a job (un poste), a contract, or a diploma, very similar to saying you 'landed' or 'snagged' it in English.

Why say ce poste instead of ce travail?

Un poste specifically means a 'position' or 'role' within an organization. While ce travail (this work or job) is grammatically fine, décrocher un poste is a very natural and standard phrasing in French for getting hired for a specific role.