Plugin creates CRITICAL ERROR

I have been using Oracle Cards plugin free version with great pleasure and no problems. However, it now appears it is the cause of a critical error 429 which causes to block me from login in on my admin. I am running newest versions of wordpress and php so that would not be the problem. I have now deactivated the plugin but would like to activate asap as my website is kind of crippeled. Could you please give me advice what I could do to solve this issue?

The page I need help with: [log in to see the link]