It sounds ok to me i mean its not like your saying anything rude your just asking a simple question, however i think doulingo should recognize that in japaneese culture these phrases are meant to be polite and formal, thus the addition of "please" should not only be a alternatuve answer, but an encouraged one
"Can I get "some" tea" doesn't not imply the same politeness as お茶をください. Also, some was not an option to chose from which would make it slightly more polite, but still not very polite in English. "May I have some tea" would be a better English translation as "may" implies a bit of politeness.
お茶 only means "tea" (any tea).
A few popular teas in Japan (from what I could get to know living in Brazil) are:
• 煎茶 [せんちゃ] = sentcha (Japanese green tea)
• 番茶 [ばんちゃ] = coarse green tea (often served after meals, I was told)
• 抹茶 [まっちゃ] = matcha (powdered green tea, the one used in Japanese tea ceremonies)
• 玄米茶 [ちゃ] = genmai tea (a blend of green tea and toasted rice)
• ウーロン茶 [ウーロンちゃ] = oolong tea (a tea preparation between green tea and black tea, more rarely called "blue tea")
• 紅茶 [こうちゃ] = black tea (though the first kanji would literally mean "red")
All of those are different preparations or blends from the Camellia sinensis, which is the tea plant.
Actually, green tea in general is literally 緑茶 [りょくちゃ]. But in Japan there are several different preparations of green tea, each one with a more specific name (like sentcha and bancha).
For a brief information on Japanese teas, see the Wikipedia article:
By the way, in Chinese, the oolong tea is written as 乌龙茶 (simplified writing) or 烏龍茶 (traditional writing), what means literally "black dragon tea" (and it is officially transliterated as "wūlóng chā", according to the pinyin system). And it is my favorite tea! ♡
My Japanese favorite tea (from the few I tried) is the genmai one. :)
Also, he just stated that he is not a native speaker and lives in Brazil. Furthermore, apart from the diasphora (that Leuenberg just posted above), Brazil is a country that speaks portuguese and there are a lot of words in japanese that are derived from portuguese words due to Portugal's contact with the japaneses