This article describes some peculiarities that you should note when installing ISPmanager 5 on an OpenVZ container.
IP address management
IP address management functions, in particular, creation and deletion of IP addresses, are not available in COREmanager 5 that ISPmanager is based on. With the control panel installed on an OpenVZ container, you won't be able to add or delete an IP address.
To resolve this issue, you should add and delete IP addresses on the container's network interface, and restart the panel to apply the changes.
You need to set up disk quotas on the parent server (Host) to be able to set up and activate quotas, as well as install the corresponding software in an OpenVZ container.