You can add a Mailchimp custom site code such as popup subscription and embedded form via custom HTML dialog and Plugins content block in ShopFactory.

Create custom pop-up forms in Mailchimp and connect it to your SF store. Sign up for a free Mailchimp account here, https://mailchimp.com/

Then start designing your own pop-up form that can be added into your shop in ShopFactory.

- Click Audience dropdown and select Signup forms 

- Choose the Signup form you want to use i.e. Subscriber pop-up (that allows you to design a pop-up signup form that can be embedded on any site.)

- Design the form using the form builder as shown in the example below:

- Save and publish the form

- Connect your site to publish your pop-up form by going to Integrations -> Custom Website - enter your Shop URL to connect it.

- Click "Copy To Clipboard"

For more information on getting your Mailchimp code - refer to their Help article, https://mailchimp.com/help/about-integrations/#Connect_your_custom_website

Paste the Mailchimp code in ShopFactory  

- you can paste the Mailchimp subscribe popup code in any content block. It will also work in custom HTML areas with "Field contains javascript code" ticked. The custom HTML code area is more suitable for the Mailchimp popup code as there won't be any visible elements initially.

- The Mailchimp form embed code will work when pasted in any block, but best suited to the custom code block and Mailchimp block under Plugins dropdown in the block editor. Pasting into custom HTML code area will also work.

Adding your pop-up code in the Custom Website contents area:

- Click Central dropdown -> Custom Website Contents

- Click the + button to add a new html code then click on the Pencil icon beside it - as shown in below screenshot

- Double-click on the newly added custom html to open the custom contents box - #4 in below screenshot

- Paste the Mailchimp code in the contents box, add an identification name

- Important: Tick "Field contains Javascript code" and select location as "Area 1" -> click OK -> Finish

- Save and Publish your shop so that the changes are uploaded online. (The popup form will appear on your website once you have connected your Shop URL in the last step below.)

- Go back to your Mailchimp account: Integrations -> Custom Website to Check connection.

An example of the pop-up form on a website:

Adding your embed form in ShopFactory using the Plug-ins content block in the Description section: