I believe before for administrative type of project all users have been added automatically

No, for administrative project you just don't have to affect every resource to the project.
Resource can directly see activities of this project in the "real work allocation" screen.
When entering some work, this automatically creates the assignment to the corresponding activity.

but resources are not in the selection list when you creating activity. So, you need to affiliate user to add as a resource to the activity or assign ticket

but resources are not in the selection list when you creating activity. So, you need to affiliate user to add as a resource to the activity or assign ticket

No, but you just don't have to assign resources to activities. It will be done automatically on real work input.
It is the magic of administrative projects.

Not quite convenient (especially for tickets) but we can live with that

hem, :blink: why do you expect managing tocket for administrative projects ?
These projects are devoted to "administrative", non project activities : holidays, sickness, training ,...

Not exactly - we are using admin type of project to link all the tickets which is not selected for current (active) project. So, this is kind of repository of tickets for different products (separate maintenance projects for each product)

So maybe administrative type is not the good one, :S as it has not been designed for this need :unsure:

May be...