Error 503 service unavailable

I use kidlogger by connected google account. For the last 2 weeks, I am not able to access my account because whenever I sign-in, an error message comes up: "Error 503. The site is getting a tuneup. The URL of the page is: https://kidlogger.net/google/callback?code=4/fHUIF5o2Gaipd0gikFqpGpCwMd71Oi1nnaTYGFXFVgo#