One of the most common reasons for the WooCommerce checkout page not showing correctly is a conflict on your store between two or more different plugins. This can be even more likely when you have multiple plugins with a functionality overlap.

In certain circumstances, WooCommerce will often disable the Add To Cart button. To fix this issue, navigate to Appearance > Theme Editor and edit your functions. php file. Afterward, on the right sidebar, click on functions.

Once you've installed and activated the plugin, you'll need to configure its settings. To do that, navigate to "WooCommerce" -> "Settings" -> "Checkout," and scroll down until you find the "Custom Checkout Button Text" settings.