Registers instead of logins

I have had everything set at https://www.koimania.cz

Now I’m logged in to my google account in another tab and when I try to connect via WPSL widget at https://www.koimania.cz it goes like if I want to register a new account. I guess it is supposed to connect me with that google account I’m logged in already.

It wants me to enter my username and password in the next step though and when I do, it returns that username and login already exist. It already exists indeed and I want to connect thru it.

The same thing with Facebook and Twitter activated.

https://www.ads-software.com/plugins/wordpress-social-login/