To add or move the customize button, you can use the Shopify theme editor to add the Zakeke customize button block inside the product page
Go to your Shopify admin > Sales Channels > Online Store > Click Customize on the theme > Go to the product page > Add block > Apps > Customize button
You can move where do you prefer the button using the Shopify visual editor, and you can change the text of the button directly from the editor
In case you want to only show the customize button, you will have to create a specific product template from inside the Shopify visual editor, where do you hide the standard add to cart button and just show the customize one - then assign that product template to the products where do you want to show only the customize button
In case you can to customize the behaveur of the button (like adding some css to it), add the following liquid code inside the product page
Go to your Shopify admin > Sales Channels > Online Store > Click Customize on the theme > Go to the product page > And add a custom liquid block using following liquid as code
If you need help or you want us to do it on your behalf, please send a message to help@zakeke.com