Microsoft is going to retired Office 365 StaffHub, which was designed for firstline/deskless workers, and replace it with Microsoft Teams.
Starting April 1st, 2019 StaffHub will be unavailable for new tenants and remove for the mobile app stores.
For existing customers using StaffHub, the service will be removed by October 1st, 2019. At this date, any access to StaffHub will be removed and a message inviting to download Microsoft Teams will be provided.