Hi! I have a friend trying to buy Bitcoin in Spain using Relai having this issue, does anyone know what the problem is? Any other Bitcoin only company in Europe to buy from? Thanks! 
Discussion
Firstly, it's cheaper to buy through SEPA transfer. That error seems specific to card use.
Secondly, in countries like Spain, it's worth taking extra effort to be as KYC free as possible. Peer-to-peer options like Peach are a little better than kyc-light Relai.
Go P2P non-KYC:
Bisq
Peach Bitcoin
Robosats
HodlHodl
Agora Desk