How do i pay at healthyareastore?

I want to buy oral minoxidil and I'm getting pretty desperate right now.
I found that Healthcare Store has a good offer.

I'm confused because they sent me an email stating that since I placed my order, they require nothing more from me, and I will pay in cash to the courier.

On the other hand, I have read posts where people stated they had to pay online even though they selected the "pay by cash" option.

Is that true? What are your experiences? Could you give me more insight?
Thank you!

*Im asking about UK