You need a tool that can copy files to or from the /storage/emulated/0/Android/data directories. I use X-Plore File Manager, which you can get at the Google Play store. You may have to Google for how to enable it to access those directories, but it can do it.
Then, you just have to copy the files folder from the old Greener Pastures save location to the new. If you reinstall before copying anything out of the old location, and avoid playing with the new version, then the old location would be the one with a files subfolder, and the new location would be the one without a files subfolder. Copy from old to new, confirm your saves now show up in the new location, and uninstall the old version.