Send invoice on order completed

On the Dashboard > Order screen, look for the “Order Actions” metabox. Enable it in screen options if necessary.

Choose “Email invoice / order details to customer”, then Update.

If you need it to happen automatically, you’ll need some code or a plugin.

This will do it:
WooCommerce PDF Invoices & Packing Slips
https://wordpress.org/plugins/woocommerce-pdf-invoices-packing-slips/

This one looks as if it will:
https://yithemes.com/blog/free-plugins/how-to-generate-invoices-with-woocommerce/

There are a couple of premium ones out there if you need more features.

@jurjenv,

It looks like @lorro was able to help you get everything sorted. I’ll go ahead and mark this thread as resolved.

If you have any further questions, you can go ahead and start a new thread.