Problem with subscription on Videoleap app by Lightricks.com - URGENT HELP REQUIRED PLEASE!!

I reside in Europe and I am trying to purchase a subscription on Videoleap app from Lightricks.com where I already had this subscription a few months back. On click the buy option a prompt appears stating that European legislation requires banks to authenticate certain transactions and thereafter it seems to be looping on the Contacting Card Issuer prompt until it hangs and terminates. Your urgent help is greatly appreciated as I need this urgently. Thanks.