Do we need to use the default "Users" eSpace user provider to use make use of ECT and BPT? OR
Can we create our own user provider eSpace and still be able to use ECT and BPT?

Hi Robert,

You can use your own User Provider espace.
The only requirement to use BPT & ECT is to have the system entities (User, Role, Group) filled with the Users you manage on your espace.
A common scenario is to when creating Users in you espace, extend the User entity and create a User as well in the system entity. When creating a Department for instance, add a foreign key to the Group system entity and create a hidden Group (eventually named "Department X"). This way, the system entities always have a "non-context aware" vision over your business model and all platform features are able to adapt to your external authentication/authorization logic.