We definitely need someone to act as a back-up for Casemiro, or at least to alternate in that role.
We need an Eriksen replacement or somebody to alternate with him. A deep-lying playmaker. Unless we do try and play Mount in that position...? Not quite sure what the plan is for Mount.
We definitely need another attacker up front. Preferably somebody who is comfortable playing in the centre forward role. I think it's more than a little naïve to put all of our eggs in the Højlund basket. We need another player in that position to give us options, either off the bench to change things up or when Højlund is injured or if we need to change formation and put both of them on.
After that, we're looking at a centre back who can act as a back-up to Varane and Martinez. Lindelöf is a good option to have and we need another.
The first three positions are the priority. If we have any budget left, then maybe a right back who is more comfortable on the ball and more fluid. The other positions are far, far more pressing, however.