To open a qbb file you need a desktop version of quickbooks same year or one newer of version the desktop backup file was created from.
As an accountant dealing with client desktop files you should instead buy the accountant version of desktop and your clients should provide a special accountant copy that you make changes to while they work on theirs.
If, instead, you are being tasked with moving this client to online then you need a trial version of desktop, restore the backup and then follow steps to export to online. The export will create another backup specific for moving to online. I feel this is important since you do not know if this is how the client backup was created or why they did not upload themselves to knline
