1. If you want to have uniform space across all the users in the organization

Login with your admin user ID at https://admin.google.com/ac/storage

Click on Manage this will take you to
https://admin.google.com/ac/appsettings/707493396369/storagesettings

By default, the user storage limit is set to off.

Change it to on and allot the space you want to allot. You can assign any amount of space. Space will be allocated on a first come first serve basis to the users.

First, create a group and add members to this group who need extra storage space.

2. If additional storage space is required for specific users.

First create a group and add members to this group who need extra storage space at https://admin.google.com/ac/groups

Create a group with any name

In the next page, set access type as restricted

Under who can join, select invited users

Now, add users who need additional space.

Now go to https://admin.google.com/ac/storage

Click on Manage

Expand Groups

Enter the name of the group, allot the required amount of space, SAVE.