Ive got the same problem and its getting me really p*ssed off!
Ive installed everything, Hitman 1 (including bonuse missions) Hitman 2 , but cant get the legacy from the store.
Ive tried - un-installing them both and re-installing, ive installed ‘get’ the ‘free starter pack’.
I’ve tried creating a new profile which people have suggested but that didn’t work.
I’ve followed everything they tell you to do , i believe the process was updated on their website on the 28th February 2019, so hopefully its something on their end and that they’re currently working on a fix , ive been looking forward to playing it but now im just losing interest