To edit a workbook, all you have to do is make your own copy of it. Click on "File", then "Make a copy". You can rename the copy and choose which Google Drive folder you want to store it in. Once you click the "Ok" button, it will be your own personal copy, which you can edit!
If you're unable to access Google Suite applications, please reach out to the Support Team and a representative will be with you ASAP.