How to access google workspace storage?

[DoubleUPh]

Hello and Good day.

As the title says, how do I access the Google Workspace storage? As to see/download files stored in there. I've already log-in as an admin and when I check the storage in Google Workspace, it shows that there are 12GB files stored in Drive, but the admin's Drive shows 0 Byte used space. How it can be? Is there another way to access the files? (Picture below)

And as of today, the storage become 0 GB.... What is the reason? How can I know who delete it? 

FYI, we have subscribed to Google Suite in 2020 before it changed to Google Workspace, and stopped the subscription in the year 2021, and now when we tried to access for data backup, it shows the situation above.... HELP