The Tarawih prayer is Sunnah (i.e., supererogatory) and it is not obligatory
Question :
I work in one of the places of business and I am not able to pray the Tarawih prayer in the Masjid, as the times for work are from after Maghrib until close to Sahur (late night just before Fajr time). Am I committing a sin in this, and how can I replace this reward that I am missing?
Answer:
You are not committing a sin by leaving off the Tarawih prayer, because it is a Sunnah (i.e., supererogatory). If a person performs it, he gets the reward and if he does not perform it, there is no sin on him. Since Allâh knows your intention, that were you not occupied with what is obligatory upon you of the hired agreement for doing this work, you would have performed this Tarawih prayer, then verily Allâh's bounty is vast. He will reward you for whatever intentions you had.
Source:
Ash-Shaykh Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 3 Pages 315-316