Issue with multi language website

Hello,

Since I have installed a plugin to make my website multi language, I have an issue to log into my WP admin panel.
I go to

https://mysite.com/my-hide-login-page

I access the WP admin login/password page but after filling info, instead of being directed to WP admin panel the system sent me to

https://mysite.com/fr/my-hide-login-page

So I get my 404 error page.

What can I do to solve this ?

Thanks for help.