Please see attached. Using Magento 2.2.1. How to I add a message next to the Create An Account Button. I couldn't find a way in Create.php. Thanks.
Maybe you'll find this link useful: https://devdocs.magento.com/guides/v2.1/frontend-dev-guide/layouts/xml-manage.html
There you'll see how to add a new block or how to modify or rearrange a block.
You need to override template file from core module to your module,
core path is,
Your theme override path is,
Now you can add your text after Create an Account button tag.