How to make automatic project build in .gitlab-ci.yml

How to make project build automatic when i merge branches? should i install cocos dashboard on image to install cocos creator of required version?

I want something like that:

stages:
  - build

build_web_mobile:
  stage: build
  image: ubuntu:22.04 
  script:
    - apt-get update && apt-get install -y wget unzip libglu1-mesa
    - wget https://download.cocos.com/Creator/3.8.1/CocosCreator_v3.8.1_linux.AppImage -O CocosCreator.AppImage # link like that one, but that one isn`t working
    - chmod +x CocosCreator.AppImage
    - ./CocosCreator.AppImage --version
    - ./CocosCreator.AppImage --path . --build "platform=web-mobile;output=build/web-mobile"
  artifacts:
    paths:
      - build/web-mobile/
    expire_in: 1 week
  only:
    - main