http://www.zenphoto.org/news/quota_manager/

Is it with this extension possible to adjust the quota for every single group and next to that for every individual user?
The description says: "You can change the quota for individual users on the Admin tab."
But I am not able to find it in ZP1.4.14.

Within the BE I can reach:
Options - Plugin - quota_manager - change options
and there it offers

• Allow ZIP
• default quota.

What do I miss?

Yes, for users and groups. You find that on each user account respectively group account on the admins tab (as long as those have rights to upload at all)

Thank you!

Seems, that I need to spend some more time learning/understanding the user- and group management in ZP.

Offtopic:
I am facing difficulties with the BE.

Every tool requires some learning ;-) Plugin options are generally general ones. In this case it makes more sense to have these setting on the actual user accounts itself instead of having one bloated option with lots of sub options.

What issues with the backend do you have?