You can use Webhooks to automate the string management between POEditor and GitHub: https://poeditor.com/help/how_to_use_the_github_webhook
- if you add/remove terms in the source file in your GitHub repo, you can use use webhooks to add new terms/remove obsolete terms in POEditor. This webhook would be linked to the file in your repo containing the source language.
- to update the translations in your GitHub files, use another webhook with a cronjob. This would run from time to time, to export the translation strings back to the files on GitHub.
Please notice that the export webhook must be triggered from outside GitHub. We set a filter for this because you can get into a loop: uploading a file that triggers the file upload which calls the trigger again. So, we recommend running the trigger by yourself whenever you like, but from a different address.

I finally figured it out. The gitlab repo i created was not yet active so you were asking for a branch but nothing was showing, i thought that master was not an option.

Here's what i'm trying to do, but still can't for now :
the team i'm on is managing localization with a big csv file. I want to import this file, but i have to do it for each language. Then i want the project to be bound to a git repo, and i have to do it for each language also.
Now, and this is a deal breaker if i don't find out how to do it : i want changes to be automatically commited to the repo, this is the only reason i'm trying this tool : collaborative work commited into a repo by people that are not technical