Failed to connect win10 desktop app with CloudFiles

Hi,
I have an account hosted with CloudFiles (one of the providers listed at https://nextcloud.com/signup/)
I was functional for 18 months.
I recently upgraded win10 desktop app, and I am no longer able to reconnect the app to the account.
When clicking big green button “Authorize access / Autoriser l’acces”, I got a warning message “Can not follow non https link on a https website. This might be a security issue. Please contact your administrator.”
I already tried to contact the company a few weeks ago, but no answer.

Is there an other user with that issue ?

Regards,
S