I face the error below when attempting to open "Extensions Page" in BC Online Production environment.
You do not have the required permissions to install the selected app. Contact your Partner or system administrator to install the app or assign you permissions.
Page View - Extension Management has to close.
What is curious is, I can open this same page in a SandBox environment. I just cannot do this in Production environment. And I am logged with the same user with the same permissions.
Permissions assigned to the current user is -->
And this same user is assigned with "Internal Administrator" license.
Also, BTW, "Design" feature only works in Sandbox too, and not Production.