Complex sentence: River Plate earned the right to represent CONMEBOL at the 2015 FIFA Club World Cup, entering at the semifinal stage, regardless of the result of the final, due to UANL being an invited team from CONCACAF and therefore not eligible to represent CONMEBOL at the tournament.
Split into simpler sentences: River Plate earned the right to represent CONMEBOL at the 2015 FIFA Club World Cup, entering at the semifinal stage, regardless of the result. That occurs due to UANL being an invited team from CONCACAF and therefore not eligible to represent CONMEBOL at the tournament.