I don't think this style will suit him tbh. Slot seems to want to use the wingers and not the FBs to provide the width.
Salah hasn't played as a winger since he was at Basel. Spent the majority of his career as a narrow wing-forward. Now his pace has reduced drastically, and he never had elite ball retention ability. If Slot's idea is for wingers to hold the width and have midfield runners support the no. 9, Salah is going to struggle.
Salah still has may be another 12-18 months left in him of top level play, but his best role is now not even as a wing-forward but as a supporting no. 10 or a slightly withdrawn forward behind a really pacy 9. In theory, Darwin at 9 with Salah just playing in a slightly withdrawn role, and focusing on just playing the final ball and finishing whatever chances come to him.
If Slot wants wants a winger who holds the width, and creates chances, we need to invest quickly in such a player at RW.