Safari have some security restriction than other browser
Then : please
1. Check on
demo.sondages.me/
and
master.sondages.pro/
if you can access (and maybe goes to answering)
2. About demo.limesurvey.org : if it work with Edge or Chrome or firefox : report the issue ouir mantis
3. About your server : same : if it work with another browser on same computer : report the issue
Assistance on LimeSurvey forum and LimeSurvey core development are on my free time.
I'm not a LimeSurvey GmbH member,
professional service on demand
,
plugin development
. I don't answer to private message.