Assign servers to customers, where is the option gone?

@Benjamin A - The menu item only appears if you allow your customers to add delivery servers, which by default is disabled.
You can allow this from backend > settings > customers > servers, or, if the customer is in a customer group, from the group settings.
Thanks, so apparently it's under:


and it's called "Can select delivery servers for campaigns *"

For the next one wondering where the option is ;-)

Somehow the way it's described in the docs made me think it was directly under the customer menu item...
Looks like a lot of things are not clear in the UI :

- I've enabled "Can select delivery servers for campaigns *" but I can't selected delivery server when logged in as a customer. Now I didn't indicate -1 to let the customer add delivery servers because I wanted to do all this when logged in as Admin to the backend. But maybe that's needed to have the option to select delivery server when logged in as User.

- When I go to "/backend/index.php/delivery-servers/index" I can see that the customer for my delivery servers is "System"... when clicking on one of this server, there is apparently an attempt at letting me specify a customer :
but no clue what I'm supposed to enter here...

Could you help me out understanding the logic behind this?
@Benjamin A - beside allowing a customer to add a delivery server, or more, you have to also tell the system what type of servers you allow your customers to add, so select that as well.
@twisted1919 I didn't want a user to ADD delivery servers, I wanted him to be able to SELECT which one to use at the campaign level.

Now I changed my mind and I'll let customer add servers, domains, etc... so I've put -1 everywhere and selected the API I'm using.

Yet I STILL have a big problem : there is no way to select the delivery server to use at the campaign level...
@Benjamin A - There is an option for that as well:
Screenshot 2019-08-21 16.00.06.png
But keep in mind, customers will be able to select servers which are either assigned to them or they are not assigned to anyone else (system servers)
OK, jiz the option is just sooo hidden :

So I finally have found the option "Campaign delivery servers" in the customer campaign, step "setup" by clicking on the "show more options" button (I wish it would have been visible in the "campaign option" box at the top as it would have made more sense than hiding it)... but now there is only this customer created delivery server available, NOT the system created delivery server...
@twisted1919 I didn't "assign" any server to my customer, I created a new delivery server when logged in as this customer.

Because apparently there should be a way to assign a delivery server but I have no clue how to fill this in: (is it a work in progress??)

OK after deleting the delivery server created inside that user, I can see the system's server now.