Students will be able to chat one-on-one using the chat window and selecting the interlocutor.
For the plugin to work as you want, you will need to go through the basic setup when installing the chat box. Follow the link:
https://imbachat.com/en/blog/post/step-step-imbachat-setup
There are shortcodes to create a group chat, you can read the information at the link:
https://imbachat.com/en/blog/post/group-chat-function