Below are the steps to Add users and assign office 365 license via Microsoft admin center.
1) Go to the admin center at https://admin.microsoft.com
2) Go to Users > Active users, and select Add a user.
3) In the Set up the basics pane, fill in the basic user information, and then select Next.
- Name: Fill in the first and last name, display name, and username.
- Domain: Choose the domain for the user's account. For example, if the user's username is John, and the domain is nerdware.com, they'll sign in by using firstname.lastname@example.org.
- Password settings: Choose to use the autogenerated password or to create your own strong password for the user.
- The user must change their password after 90 days. Or you can choose to Require this user to change their password when they first sign in.
- Choose whether you want to send the password in email when the user is added.
4) In the Assign product licenses pane, select the location and the appropriate license for the user. If you don't have any licenses available, you can still add a user and buy additional licenses. Expand Apps and select or deselect apps to limit the apps the user has a license for. Select Next.
5) In the Optional settings pane, expand Roles to make this user an admin. Expand Profile info to add additional information about the user.
6) Select Next, review your new user's settings, make any changes you like, then select Finish adding, then Close.