I’m new to the user-access-manager plugin, but it may be something like this, using the UAM API:
global $userAccessManager;
$uamAccessHandler = $userAccessManager->getAccessHandler();
var_dump( $userAccessManager->getUserGroups() );
That would dump out the contents of that getUserGroups()
method, which may be a jumping-off point to the next step (actually checking that the user is in the group).