"The trees have apples."
Translation:Die Bäume haben Äpfel.
The forms of German verbs change depending on the subject. You can see remnants of this in English, e.g. "I have", but "he has".
haben (to have)
ich habe (I have)
du hast (you [singular informal] have)
er/sie/es hat (he/she/it has)
wir haben (we have)
ihr habt (you [plural informal] have)
sie/Sie haben (they/you [formal] have)
"habt" is used with "you" [plural informal]. "Die Bäume" (the trees) can't be replaced with "you", but they can be replaced with "they". Therefore you have to use "haben" and not "habt".
Having said that, the whole sentence sounds a bit odd to me.
You can access the special diacritical marks via a long press on the letters. OR You could install a different keyboard on your phone or install added languages to your current keyboard. Default Apple, Samsung, and Android keyboards allow this. Then you can swipe to type words.