Not sure what Apple is doing buying Credit Kudos because Credit Kudos is not a bank, it is not a money lender, it is a credit reference company that gets hold of banking data and using it's algorithms it then assess whether the person or business is good for credit or not. This is from their website:
So whoever was the one that originally stated that Credit Kudos is a banking startup needs their head examining because the company does not provide any banking services whatsoever and before anyone jumps in to say they are because of the services they provide, credit referencing is a 'financial' service, not a 'banking service'. Banks never do their own credit checking because it is always done by a third party company registered with the FCA to offer such services.
The only thing I can think of as to why Apple would purchase such a company is that to offer Apple card in the UK/Europe, Apple would require a UK/European credit reference company to carry out the checks on UK and European citizens wanting the card because such a service cannot be done by a US company because the US company is not allowed access to UK/European citizens banking data, whereas a UK one would.