Hey Augisek_, thanks for getting in touch and I am sorry to hear about the issue you're having.
As it stands, I can confirm that we have received multiple player contacts about the exact same problem and our development team is already looking into it.
In the meantime, as a temporary workaround, you can try purchasing your credits through Ubisoft Connect launcher (Store tab) or alternatively, visit our
online store.
Apologies about any inconvenience this may cause and as soon as we will have further updates, details will be posted in our official forums so keep an eye!