Follow the directions that are shown. EXCEPT! What you need to do before uploading the server files to the Server through FilZilla is you need to run the custom_server.jar twice. When you run it the second time it will generate the EULA.txt file in the directory and then you can edit it and set it to true. After you have done that THEN upload all the files to the server.
If you have already uploaded all the files before doing this. Delete all the files on your server except the eula.txt and then start up the server with Vannila Minecraft 1.12.2 Then follow my directions above and upload all your files.
