1) You extract from data_graphic1(.big) -> data/sceneassets/radiosity/stadium_13.rad via CG File Explorer. The file stadium_13.rad will be then in data/sceneassets/radiosity/.
2) You put all of kotiara6863's Anfield files where they belong.
3) You regenerate the files with FHL-BH-Editor.
4) In data/sceneassets/radiosity/ you delete or rename stadium_13.rad so the game can't find it. You can also put it in a new folder if you like.
And that'a all!
Please keep in mind that you have to do this everytime you regenerate files from now on cause the game will use the original rad file from data_graphic1(.big) if you don't put it back to data/sceneassets/radiosity/ before regenerating.
It's the same method to make Wizard's Borussia Park or RavenFCB's Stade Vélodrome work.