The link was wrong, it's still there:

https://github.com/zoton2/LiveSplit.Scripts/blob/master/LiveSplit.GTA3-README.md

Thanks for pointing it out, I'll fix it ASAP

Go to the community discord and post it in #gta3. You can find the link in the pinned thread.

I have a question and it may not be related to the topic. If I made a better run, do I edit my already existing run or do I submit a whole new run?

you shouldn't edit previous runs, always submit new one

only edit to change comment or video links, or if timing/date/platform was wrong or whatever