How can I enable a discount popup for subscribers on my Dawn-themed store?

Store Design
1

The Shopify sample store here https://kindahotsauce.shop/ includes a very nice popup to "SUBSCRIBE AND GET

10% OFF YOUR PURCHASE". When minimized, it appears in the bottom left corner. I would like to enable the same on my store. I use the Dawn theme. Any pointers on how this is done?

2

Hi. Looks like example store use this app https://apps.shopify.com/postscript-sms-marketing