How do i make a intro gui script? like the one in the video

I have the actual gui i want but like the script is making me trip. I went on Youtube and looked for tutorials. And none of them never worked for me. half the time it was outdated so that's probably why it wont work but what i'm trying to do is like this one but it just never worked for me

https://www.youtube.com/watch?v=QMFp8alXCNk I also opened the script analysis thing and it didn't detect any problems

please help