Hi, most probably it’s htaccess issue (if you are using Apache server). But I couldn’t login with above login details (it redirected me to http://my-indemnisation.com/login.php).
Please let us know your site’s wp-admin login details and FTP details as private reply so that we can look into the issue.
There was no .htaccess file in the site’s root directory. I have created it, and applied “medium privacy more compatibility” settings scheme in HMWP, and it’s working fine now. Please check and let us know.