(issue) fixed button displaying dynamic content

Hi everyone !
i’m writing here because i can’t find a solution by my own for now.
I’m trying to showcase my (video) projects on the home page and i need to show informations about the project on screen by clicking on a “+” button, which is fixed. so i need to pick cms information and display them in a fixed div at the top of the screen which content change if i scroll down to another project but the div which contain the projects informations stay fixed. i tried several things but i can’t achieve this, is someone can help me?

Here is my public share link: LINK
(how to access public share link)