Letsencrypt using DNS to verify domain

I have spent good bit of hours today trying to setup access to my nextcloudpi from outsude.
I have created a hostname at No-IP.
I’m following the guide but not sure how to deploy the TXT record pointing to _acme-challenge.petal.serveftp.com.

When I run
“sudo certbot -d petal.serveftp.com --manual --preferred-challenges dns certonly” command and it ask to deploy the TXT file, I’m not sure where and how to depoly the file.

This is where I’m lost
----- You’ll need a domain and access to the DNS records to create a TXT record pointing to: _acme-challenge.yourNCP.yourdomain.tld

Here’s document I’m trying to follow.

You need to update the TXT record in your DNS configuration. As usual aunt G. can give advice how to do this with a No-IP.com domain: