@Moin referenced the guide above: Create, download, and restore a backup of your Discourse database
In my experience version need to be similar and
the new installation must have the same plugins installed otherwise the restore usually errors out.
Following the guide works… Keep trying @Sidi_Codet If you are going to successfully self host Discourse you are going to need to be able to do things like this, unless you have someone manage your server and Discourse for you. Keep at it, things get easy as you go. 