Ecwid is designed to work on any platform. Ecwid supports responsive layout that allows Ecwid shops to adapt to different screens.
Facebook has certain restrictions hindering the work of applications on mobiles, and it impacts all Facebook apps, not only Ecwid.
Please see the detailed reasons here: https://support.ecwid.com/hc/en-us/articles/115002965485
In such cases, we commonly recommend our customers to post a link to their Ecwid Starter Site (yours is always available in your Control Panel > Settings > General > Starter Site) somewhere on their Facebook store page, so that the customers viewing the site from mobiles could open your store and make orders. Starter Site has a fully responsive layout, so it will be displayed accurately on mobiles. You can check its appearance in our demo store: http://www.ecwid.com/demo?iphone&lang=en#!/~/category/id=0&offset=0&sort=priceAsc
To get your store visible on mobile devices in Facebook, please follow the following instructions:
1) Get your starter site link by going in your Ecwid control panel to Settings > General > Starter Site and copy the link below "Your starter site".
2) Go to your Facebook page and click on the "Call to Action" button,
- click on "Edit call to action",
- choose "Shop Now Button",
- and under "Website" paste the starter site link and click on create.
Main article about Facebook: https://support.ecwid.com/hc/en-us/articles/207806665-Facebook