Bobby Krlic has said on interviews that the album version of the game music would be recomposed for release purposes, making the OST more player friendly and creating a narrative for the album. There are a lot of tracks missing from the iTunes album but it's intentional. You can't go more AAA than hiring this guy who has worked with Bjork and Atticus Ross as a producer and did the soundtrack for Midsommar.
Short bio:
Bobby Krlic (born 1985),
[1] known by his stage name
The Haxan Cloak, is a British composer, artist, music producer and musician. Over the past decade, Bobby Krlic has created music under The Haxan Cloak, releasing two full-length albums (2011’s
The Haxan Cloak and 2013’s
Excavation).
[2][3] As a producer, Krlic has worked with artists including
Björk,
[4] Father John Misty,
[5] Khalid,
[6] Troye Sivan,
[7] Goldfrapp,
[8]serpentwithfeet,
[9] The Body,
[10] and noise-rock band
HEALTH.
[11] As a composer, Bobby’s credits include
Midsommar[12] directed by
Ari Aster,
Michael Mann’s
Blackhat (in collaboration with Oscar-winning composer
Atticus Ross),
[13] Rockstar Games’
Red Dead Redemption 2 (in collaboration with Swans)
[14] and major network television shows
Snowpiercer,
Angel of Darkness (TNT)
[15] and
Reprisal (
Hulu).
[16]
en.wikipedia.org