Copy the layout file to your theme.
Copy the customer account creation layout XML file from below location
to your theme that you’re editing
If the template folder does not exists then create a template folder in the given path
replace the below line of code of layout file (which one is copy from core magneto)
<block class="Magento\Customer\Block\Form\Register" name="customer_form_register" template="form/register.phtml">
<block class="Magento\Customer\Block\Form\Register" name="customer_form_register" template="Magento_Customer::/form/register.phtml">
Copy the html code from below location and paste into register.phtml (which one is created in theme directory)