The reason your colleague may be seeing a blank or different list of schools on their Schools page than you is a result of our Choose Your Schools Feature, which we recommend reading more about here: About the Choose Your Schools Feature
School approvals are company based, meaning if a school approves your request to connect with them, that approval will carry over for every user connected to your company's profile.
However, each user connected to the company profile will create their own separate list of schools to have on their own individual Core School List. They can do this by following the steps here: How to Find and Request Access to a School
While there's not a way to mass-add all approved schools to a user's account, all users do have the ability to toggle between seeing only information for the schools on their Core Schools List and All Schools the company is Approved at. Again, this does not add the approved schools to their Core Schools List, but does enable them to see jobs, applicants, etc. of all schools the company is approved at, which would otherwise be hidden. Here's steps on how to do this: How to Toggle Between Your Approved Schools and All Other Schools