To be able to share content on Box externally you have to take Box 100 course (just have to watch a 5 min video)
https://it.uclahealth.org/support/guides/guide-for-box
“Upon completion of this course, external collaboration will be enabled for your Box account within 1 business day.”
NOTE:
Mednet Box considers other UCLA personnel to be “external collaborators” so you have to complete the above course to be able to share with anyone with an `@g.ucla.edu` email address.
It seems inconsistent whether you need to include the “.g” in the email address (eg ID@g.ucla.edu vs ID@ucla.edu) when sharing to non-mednet collaborators. If the sharing request is sent but the recipient does not get access to the shared content try removing/adding the “.g”