If you are using iTunes 12.2 and newer, iTunes by default no longer share its Library XML with other applications. You will have to share your iTunes Library XML with BRIO manually.
To do this, go to iTunes > Preferences > Advanced, and check Share iTunes Library XML with other applications.
When you next go to This PC>My Music>iTunes directory, you should now be able to see iTunes Music Library (XML file Type) visible in this directory. If it is visible, BRIO would be able to scan the iTunes Library and you would find them under Library in Albums, Tracks, Artists and Genres.
[Note: BRIO Standard supports Apple Lossless (ALAC). Due to AAC licensing, BRIO Standard (server) does not support AAC format. Subscribe to BRIO Mobile plan if you wish to get the BRIO server with AAC support].