For steps on how to create multiple users through the use of CSV files, Powershell, ActiveDirectory, and Exchange migration, please refer to this Microsoft support article:

How to Create Users

1. Login to Microsoft 365 using an Admin account. This can be a Global admin, or User management administrator
2. Go to the App tile on the top left, and click on Admin
3. On the Admin home page, in the User Management tile click on the Add user button
4. Fill in the appropriate information for the user, and select Add to finish creating the user

note: Refer to the Microsoft KB article in the additional information section for detailed instructions on advanced user creation