NOIP.com does NOT appear to be on the PSL
Although you may be able to get certs for that domain you will be challenged by many others for the very few certs that are allowed (only 20 per domain per week).
You should review the PSL and see if you can obtain a name from one of the domains already on the list.
PSL here referring to the Public Suffix List, a list of domains where the owners of each have asserted that subdomains are in use by various members of the public.
You can also, of course, purchase your own domain name and avoid these issues altogether.
I think the OP may have meant to write no-ip.com (with a dash). They are listed on the Public Suffix List and many people have obtained certificates for their no-ip.com domains.
EDIT: I did notice that they run their corporate website on noip.com but host customer domains on no-ip.com, which is definitely confusing. If you tried to get a certificate and failed it might be because you forgot the dash (-).
Does your home IP have port 80 blocked? e.g. can you access http://username.no-ip.com/ directly or do you have to use to use a weird port like http://username.no-ip.com:8080/?
So, just to confirm: @Ondrej2005 What is the actual domain you are using?
If you don’t care to share the FQDN, that is OK.
Just reply with the domain name.