Need advice about e-commerce with low conversion rate

Hello,

I am currently working on a digital campaign for an e-commerce that sells prints of art photography. Our market positioning is middle-end: high quality for a reasonable price, with a few bonuses such as a satisfaction guarantee and free shipping.

The challenge I am facing is that soft metrics are quite good ― 2 minutes of average visit duration and 3.5 pages/session ― but almost no adds to cart or transactions. I observe the same pattern regardless of the traffic source (mainly Google organic, Google ads and Facebook ads).

I have the feeling that something discourages visitors from adding to cart, but I cannot identify what it is. Any clue?

Here the link to the website: https://en.photo-to-go.com/

Thank you!