Then you re going to experience the most amazing moment up here 這裡的up here是什麼意思？為什麼要up不直接用here就好？？？

up/down 的應用 是很主觀/抽象的.有可能與 真正的 (物理上的 或是心理上的)高度 有關.也有可能無關.
不過 一般來說 up會用在 較優的處境 down會被用在 較不優 的處境

例如說:
1. There are a lot of jobs up north. There are few down south.這裡的up/down 與高度無關.只是對應地圖方向.
2. There is a bank down street. There is a Starbucks up 3 blocks. 這裡的up/down 與任何事情都無關.只是習慣.

所以你的問題:
up there or down there, or even just there - all are fine. 隨便你用　都可以．

有可能這裡(here)是一處「位置很高的地方」，所以用up。
如果這裡是一處位置很低的地方，則可把up換成down。

up :-adv particle; the verb entry for combination with up=up here;
as suggesting readiness for activity
eg:=Up with them;
Up with you;
There's something up here; something unusual is happening, planned .
Used vaguely in a way similar to the use of down, round, over, across , to the place in posting.in which the poster here is, was, will be:-
eg:-He came up here to me and asked the experience about the amazing moment.