Google has made some changes to their email system and we are working on aligning the experiences for our users. The starred and important folders will no longer exist on your Google account in Outlook. For the Important folder, those messages will now appear in your Focused Inbox that you can turn on and off in your Settings. For the Starred folder, we will ensure those messages are now Flagged and you can sort by Flagged messages in your inbox.
Note: This functionality is not completely equivalent to Starred folder because the Flagged filter only shows flagged messages in the current folder.