Can you create a loading screen in redm?

Hi, I wonder if you can create a loading screen in redm.

I tried with my FiveM loading screen and changed the fxmanifest but it doesn’t work ! It doesn’t show the loading screen. It is the same as the basic one.

fx_version 'adamant'
game 'rdr3'
rdr3_warning 'I acknowledge that this is a prerelease build of RedM, and I am aware my resources *will* become incompatible once RedM ships.'

files {

loadscreen 'index.html'

Do I need to add extra stuff so the loading screen can work ?