Isak eventually signed for Liverpool in the final days of the summer market for £125m. However, the negotiations dragged on throughout preseason and Mac Allister says Liverpool's players were frustrated following the story.
"At the beginning, it was a big thing and after a while we got a bit tired because it was too long," Mac Allister shared with TNT Sports.
"But we all know the player he is. He is going to be really, really important and we are happy to have him here."
He added, "Maybe the other club is not happy but that's the way football works, they paid quite a lot of money so I think it's good for both clubs.
"It's good for him because it's what he wanted, we are so happy to have him because we know the player that he is and we suffered against him a couple of times as well."