NoRecords
Fatal
No valid A or AAAA records could be ultimately resolved for onlyoffice.lechambon.fr. This means that Let's Encrypt would not be able to connect to your domain to perform HTTP validation, since it would not know where to connect to.
No A or AAAA records found.
You do not have a DNS Record that is A or AAAA or CNAME for the Domain Name.
You need to add a DNS Record for the Domain Name with your DNS service provider.
Let's Encrypt is a public Certificate Authority and must validate your host name using the public internet starting with the DNS.
There are ways to get certs for purely local names. Some discussion is at below topic. You will also find others posts here talking about smallstep and other methods. Try searching