"We always study together."
Translation:Ni ĉiam studas kune.
you are not the object being influenced by the verb. instead, in this case, you are the one doing the action. a good example sentance of the accusative is "Mi manĝas la pomon" You are the topic and you perform the verb upon the said object (i.e. the apple). Hope this helps
Because that would make it "We always to study together."
The "to study" is the inifinitive, the form of a verb for talking aobut it: You're not studying (studas), but you're talk about to study (studi).
E.g. We always try to study together. What do you do? We try. That's the action of the sentence; it gets the -as suffix. Next you talk about something that you try: What do you try? "To study together." That's your infinitive, which in English usually starts with "to", and which in Esperanto gets the -i suffix. So: "Ni ĉiam prov-as stud-i kune."