Questions & Answers about Мы договорились встретиться в кафе у метро и обсудить план на завтра.
Russian often uses a past-tense verb to describe a completed agreement made earlier: Мы договорились... = We (already) agreed.... The future action is then expressed by the infinitives (встретиться, обсудить), not by changing договорились to future.
Договориться = to come to an agreement / to arrange (together), usually implying a mutual decision after discussion.
Согласиться = to agree (to something), often implying one person accepts someone else’s proposal.
So Мы договорились встретиться... feels like We arranged to meet... (both sides participated).
A very common pattern is: договориться + infinitive = to agree/arrange to do something.
Example: Мы договорились позвонить вечером. (We agreed to call in the evening.)
You can also express it with a noun: Мы договорились о встрече. (We agreed about the meeting.)