Implement Git on my server

Hi Freelancers,

I'm trying to install Git on my server and I'm facing an issue.

I got access to remote server in SSH but as a simple user, not as root.

I already create the repository
I already commit files
set the gitignore
I've created a ssh key and install it on Gitlab as well
I already set gitlab project

I get a permission error when I try this command :
git push -i ~/.ssh/id_git_ed25519 -u origin main

I get error, I can't push

Support is telling me, the is an error with .gitconfig file
They said it is not at the right place

Please contact me if you are able to help