Problems exporting entries from ExpressionEngine 3 with Feed Me 2 beta plugin
Just some additional context here, we're referring to the guide for Feed Me 2 here, which leads to the Gist here. This Gist has not been tested with EE3, but should work just fine for EE2.

That Gist is really just a guide to get you started quickly with an export. It's in no way a requirement, as you can simply create your own JSON or XML templates in Expression Engine to output your content. Once that's done, its over to Feed Me to continue as normal.

You might like to refer to https://github.com/rsanchez/json or simply write your own JSON/XML templates.