Copy the layout file to your theme.
Copy the customer account creation layout XML file from below location
/vendor/magento/module-customer/view/frontend/layout/customer_account_create.xml
to your theme that you’re editing
/app/design/frontend/<Vendor>/<Theme>/Magento_Customer/layout/customer_account_create.xml
If the template folder does not exists then create a template folder in the given path
/app/design/frontend/<Vendor>/<Theme>/Magento_Customer/templates/form/register.phtml
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">
to
<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)
vendor/magento/module-customer/view/frontend/templates/form
app\design\frontend\vendor\theme_name\Magento_Customer\templates