Berlyn Actually you can install it in any webhost. From my understanding composer is not really a requirement.
You can just install composer on any windows machine, download the files and then upload them to a web host of your desire. You just need to make sure that the web host has all the requirements Flarum needs for it to run properly or else it would break quite easily.
Bruno usted puede descargar los archivos por el composer y subir a un servicio de hosting normal.