Copying WordPress Install to Another Location

I am attempting to copy an existing wordpress install at https://stega.jp/main (url: stega.jp) to https://stega.jp/en.

The problem I am having is that the new install does not contain any of the old content. I copied the old install in its entirety to the new location and assigned it to a new database.

I’m sure I’ve made a fairly basic error.. I think probably something to do with the database, but I can’t seem to get it to work out. Any help would greatly appreciated. Apologies if I’m not providing enough information.

Thank you.