There is no crond.service on Arch Linux. As the Arch Wiki makes perfectly clear:

There are many cron implementations, but none of them are installed by default as the base system uses systemd/Timers instead.

Consequently, if you want to use cron, you have to choose which of the many implementations you will install, and then start that specific service.

You don't just randomly type systemctl enable nonexistent.service and then wonder why it isn't running...

If you want cronie, then you install cronie and start it with:

pacman -Syu cronie systemctl enable --now cronie.service 

The Arch documentation is generally very clear; rather than just linking to it, actually reading it yields surprisingly effective results.

There is no crond.service on Arch Linux. As the Arch Wiki makes perfectly clear:

There are many cron implementations, but none of them are installed by default as the base system uses systemd/Timers instead.

Consequently, if you want to use cron, you have to choose which of the many implementations you will install, and then start that specific service.

You don't just randomly type systemctl enable nonexistent.service and then wonder why it isn't running...

If you want cronie, then you install cronie and start it with:

pacman -Syu cronie systemctl enable --now cronie.service 

The Arch documentation is generally very clear; if you read the pages you linked to more carefully, you should find out what you need.