There are four steps to getting started with Basic Mobility and Security:
Activate Basic Mobility and Security by going to the Office 365 Security & Compliance.
Go to Basic Mobility and Security (Preview).
Create device management policies, and apply them to groups of users that are set up in security groups. We recommend that you start by deploying the policies to a small test group. For more info, see Create device security policies in Basic Mobility and Security.
Users who have had a policy applied to them are prompted to enroll their devices when they try to access Microsoft 365 data. For more info, see Enroll your mobile device using Basic Mobility and Security.
For more details, see Set up Basic Mobility and Security.