Would you translate this phrase as present tense?, as I take it you're brazilian :) There doesn't seem to be anything that signifies past/present/future tense, so normally that would be read as present tense?
The verb ending shows us what tense the sentence is, this is the why you can omit the subject/pronoun of the sentence. Past: Ele não me adicionou no Facebook / Present: Ele não me adiciona no Facebook / Future: Ele não me adicionará no Facebook. These are simple tenses, we have others too. But Duo's doesnt show me anything that I could assume this sentence is future, especilly the verb! I mean, you can use the verb in present tense since you add something else to show it is future (like in English) = I travel this weekend (Viajo -presente- este fim de semana -future)
It's certainly a bug in the text-to-speech, but I guess Brazilian people pronounce it as "Fay-see-boo-key" (that is: the "e" is actually pronounced, the "oo" turns into a Portuguese "u" sound, and an extra "i" vowel sound is added at the end of the word)