Hello,
Unfortunately, there is no option in theme settings to display the promo popup only on the homepage.
It is set to be displayed when the website is first loaded on every link.
You can enable the promo pop up from Theme Settings >> Shop >> Promo Pop up.
Screenshot for Clarification: https://ibb.co/mh61Ym4
To edit the promo popop you need to edit the HTML Block used in the promo popup text in the settings as mentioned above.
Best Regards.