[1] In 2021, after finishing his formation, he was assigned to Lugo's farm team Polvorín FC in the Tercera División RFEF.
[3] He scored his first senior goal on 31 October, netting his team's second in a 3–1 away win over UD Somozas.
[4] Castrín made his first-team debut for Lugo on 2 December 2021, starting in a 2–2 away draw (4–3 penalty win) against AD Unión Adarve in the season's Copa del Rey.
[5] He made his professional debut fourteen days later, starting in a 1–2 home loss against CD Mirandés, also in the national cup.
[7] Their father, Juan López, also played amateur football for local side Riotorto CF.