You can organize your private members into groups. Members from different groups have access to different channels.

1. Go to "Private Members”->“Manage Group”. Click on “+New Group”. Enter your group name.  (Go to Settings> Advanced Options to enable Group or Contact us if there is no “Manage Group” menu in your account.)

3. Go to “Channels”, click on “Edit” to set which groups have access to the channel. Select "All" group, if you'd like all the private members have access to the channel. 

4. Go to “Private Members”, add a member and select a group. Or click on the “pencil” icon to update the group information. To batch add private members into groups, please refer to here. To add members into groups via SSO login, please refer to here