How to batch assign users to a group

In Docman v1.6.7,

I have created multiple Docman "Groups" (etc Standard, Professional, Delux,..) , and each group has a number of users/member assign to it.

In the Documents Permissions setting, "Viewers" is set to the target group so that only members in that group can "View & Download" the document.

Problem 1
Howerver now in Docman 2.0, it no longer have its own "Docman Groups" where it require to create the group using Joomla->Users->Groups, and have to manually assign each each to the correspond group. I have >200 users in my website, do i really need to assign each user to the group one by one?(Open each user profile and siggne the user group).

Problem 2
When "Registered" user login to my site, they can "View & Download" documents based which group they have been assigned. This is done via the Document "Viewers" setting, however, since Docman2.0 don't have the "Viewers" setting anymore, all documents under the Category will be visible to my client. How do i share the files based on which group the user belongs too? Can you show me a step by step guide?

Thank you.