What is bad user experience?
This is a store that sells medical books and accessories for narrow range of customers - products only for specific diseases. These are products required by people of all ages so the user friendly interface is something that should be implemented. People accustomed to buying online or surfing the web may buy products too but it's more difficult. Not experienced internet users will not be able to buy anything.
What things I would point here as obstacles? Required fields on the right sight of the screen. All of them are obsolete because can be replaced with a checkbox. For English speakers - the text next to these fields are questions about confirmation. I don't know what should I write in the fields: yes? I agree? of course? What is more - required fields make styling crash and text is unreadable.
Fields on the left are expandable by clicking "company" or "user" buttons but clicking on checkbox "Other address to send" the new fields appear on the right, expanding ridiculous styling even more. What's with all the white, unused fields?
Text hoover changes cursor, and one of the texts next to the field (RODO) is not explained anywhere.
Here is the address for the web page in case you want to find more things:
The shop itself is very useful and could have many potential users. Let's hope that by pointing this issues they will resolve them.