Zeineddin joined Platense at the age of fourteen, having previously spent three years with Vélez Sarsfield. He was promoted into Platense's first-team squad during 2020, with the centre-forward penning his first professional contract on 13 November. Zeineddin made the substitute's bench for a Primera Nacional match with Deportivo Morón on 5 December, with manager Juan Manuel Llop subsequently selecting him to come on with thirty-three minutes remaining of a 1–1 home draw; he replaced Daniel Vega. He made his first start on 11 December away to Estudiantes, which preceded one further appearance in a campaign that ended with promotion.
