COMPUTER
In Team Settings or Group Settings, you can choose to a) Allow Members to Chat and b) Approve Non-Admin Posts. You can also edit the About section as well as change your team/group name.
In far right under the cover photo, click gear icon.
Click Team Settings or Group Settings.
APP
In Team Settings or Group Settings, you can choose to a. Allow Members to Chat and b. Approve Non-Admin Posts. You can also do multiple other actions.
Tap your team or group, then tap gear icon in top right.