Presently it is not possible to restore directly from an automatic backup (oneway backup function to a distant drive different than icloud). You have to first download all the files and folder from the distant drive (ex google drive) then zip them and then send them via airdrop to the ipad and open it with Goodnotes.
And it’s even more difficult if you have selected the option to backup .goodnotes and .pdf files because you need to delete the .pdf files ...

Please add a restore function simple to use