"Uso mis piernas para jugar fútbol."
Translation:I use my legs to play soccer.
Grammar websites list "jugar" as requiring "a" in this configuration only. Verb + a + noun. https://www.lawlessspanish.com/grammar/verbs/verbs-with-a/
From what I have read this rule was not observed in US/CA/SA. This combined with the influence of the English equivalent without a preposition "to play football" led the RAE to accept the omission of the "a" as an Americanism. Spanishdict gives some good examples of both here. http://www.spanishdict.com/translate/jugar
I see nothing wrong since it is the same answer I gave. It is a new sentence so they just don't have their database complete. I will report it.
El fútbol = soccer = English football.
El fútbol americano = American football.
Context sometimes overrules the need for the adjective when it is clear that American football is being discussed.