step 2 bug Domain Verification

at the 2 step: Domain Verification i got the message below.
no files to download, no way to install it.
i installed without any troubles sslzen in my other website: https://sankara.fr, on the same ip dedicated serveur.

please i do not understand this bug

regards
Raphael

screen and message in admin part:

Which domain verification process would you like to use?

HTTP
10 mins
Step 1
Create .well-known/acme-challenge folder

Step2
Upload verification file(s)

DNS
7 mins
Step 1
Identify your domain host

Step 2
Add a domain TXT record

The page I need help with: [log in to see the link]