Unable to install Duniter

My attempt:

$ sudo yunohost app install https://github.com/duniter/duniter_ynh
Available domains:
- xxx.net
Dedicated domain name on which no application must be installed. Install will be done on root path. (default: xxx.net): 
Administrator. Must a YunoHost user.: xxx
Warning: 'yunohost app checkurl' is deprecated and will be removed in the future
Warning: Unable to install the app in this location
Warning: Path not available: xxx.net/
Warning: sudo: duniter: command not found
Warning: dpkg: warning: ignoring request to remove duniter which isn't installed
Warning: Unknown service 'duniter'
Warning: usage: yunohost firewall disallow {TCP,UDP,Both} port
Warning:                                   [-h] [-4] [-6] [--upnp-only] [--no-reload]
Warning: yunohost firewall disallow: error: too few arguments
Warning: duniter has not been properly removed
Success! The SSOwat configuration has been generated
Error: Installation failed

As stated, you must specify a “Dedicated domain name on which no application must be installed.”.
Haven’t you already installed an application on xxx.net in any sub-path… ?

What about a subdomain?

yes, something like duniter.yourdomain.tld would work. “Domain” is a bit confusing because you usually think of a full domain (e.g. yolo.com), but for yunohost there’s no notion of “subdomain”. “swag.yolo.com” and “yolo.com” are both “domains” with apriori no hierarchy between them.