Thanks for reaction.
Hope you’ve seen a note at the top of page saying:
“Don’t forget to make a full backup of your files and database before trying.”.
That plugin does a lot of database and filesystem operations and only full backup may restore the state.
That plugin is not supposed to provide any “Backup & Restore” functionality by intent – there are other great plugins and hosting provider tools (I suggest to use them instead of plugins when available) for that task.