https://wccftech.com/hitman-3-hitman-2-progress-transfer-issues-io-interactive-response/

One of the big advertised features of Hitman 3 was the ability to carry over much of your progress from Hitman 2, including your profile rank, location mastery XP, completed challenges, and unlocked cosmetic goodies. Doing so requires you to sign up for an IO account, then transfer your Hitman 2 progress by logging into a special website. Well, unfortunately, the transfer progress isn’t working well at the moment as swarms of people try to transfer their progress at once. IO Interactive is well aware of the problem, and are “hard at work” trying to get the transfer system operational again…

HITMAN 3 has arrived and everyone wants to play at once. We're tracking and will have everyone in the game, with their progress as soon as possible.