Not an expert (I followed the instructions with 19.04 but can't get it working!) but would suggest simply changing to
"The following packages are needed: krb5-user, samba, sssd and chrony"
The rest of the document makes references to chrony, so it looks like this one reference to the NTP [package] was missed.
Versions of the document for earlier distributions refer to ntp only. For later distributions, it was switched to chrony, but this one reference was missed.
Not an expert (I followed the instructions with 19.04 but can't get it working!) but would suggest simply changing to
"The following packages are needed: krb5-user, samba, sssd and chrony"
The rest of the document makes references to chrony, so it looks like this one reference to the NTP [package] was missed.
Versions of the document for earlier distributions refer to ntp only. For later distributions, it was switched to chrony, but this one reference was missed.