Make sure that the app is enabled, and then embed the form on the storefront/page where you wish the form to be. Please refer to this article on how to achieve that: Embed the Form on Store: Inline
Go to the edit section of the form you embedded to the storefront in the previous step.
Go to Form Settings -> Form load as popup -> Check the Enabled form as a pop box
Select where you want the form button to be among the 4 position options or place it anywhere in the page by choosing Custom placement option. You can place the form as a popup anywhere in the page by going to the storefront, clicking Inspect and then copying the class id into the Class ID field.
When placing a form as a popup button on a custom part of your page, first right-click and select Inspect. Then, hover over different parts of the code to see them highlighted on the page. This helps you confirm you’ve selected the correct section. From the highlighted div class, copy only the text within the quotation marks up to the first space, and paste it in the Class / ID of Position field.Go back to the Customize Theme page and click Save. Your form will show on the selected position in the storefront.
Watch the video for detailed instructions: