syncing server files to cloud for read only access off site on a budget

Client has like almost a terabyte of office 365 documents on the server. They want read only access from the field.

I figured we already pay for office 365 why not uplaod them to a share point site. It was easy enough to create and assign rights to. Invites sent. But.

When I tried to upload the folder with the terabyte of data it never even finished counting the files before it blew up. Cannot handle an upload that big. I can do smaller chunks but it will take much longer. And seems to only sync to one drive, which we are not using? So this does not seem vialbe at all.

What would you all suggest on a budget? Something like box.com would work for it is really expensive...