How to share contact groups now in Office365 as 'Public Folders' don't show in New Outlook

I have used contact lists in 'Public Folders' for a team of users for many users, now users on NEW OUTLOOK cannot use or see these. 

What do I use now to import these contact lists (csv or whatever) into what medium on Office365, a shared mailbox, a public folder mailbox,  a distribution list, contact group, M365 group to hold all these lists for different clients?

Note: All users should have the ability to edit the contact lists AND send email (like its an Outlook Address Book). It must be mail-enabled as the users just need it to send emails to.