I am no longer involved in FiveM and apart from the occasional dependency bump this project is unmaintained. PRs highly encouraged!
You need vue-cli 3.x.
npm install -g @vue/cli
git clone https://github.com/calumari/fivem-vue-boilerplate.git html
cd html
npm install
npm run build
...
files {
'html/dist/index.html'
}
ui_page 'html/dist/index.html'
npm run serve