The original .service file lists network-online.target as a dependency in both After= and Wants= directives, which, if one's using systemd-networkd (assumed every user of this particular app), already satisfies the dependency on systemd-networkd:

systemd-analyze critical-chain zerotier-one.service

zerotier-one.service @13min 6.079s
└─network-online.target @7.650s
  └─systemd-networkd-wait-online.service @735ms +6.915s
    └─systemd-networkd.service @694ms +39ms

Overwriting that may make zerotier-one start before network is up which is bound to cause problems, like:
zerotier/ZeroTierOne#1259

As per https://wiki.archlinux.org/title/Systemd#Running_services_after_the_network_is_up

If using systemd-networkd, systemd-networkd-wait-online.service is enabled together with systemd-networkd.service. Check if this is the case with systemctl is-enabled systemd-networkd-wait-online.service. If it is not enabled, then reenable systemd-networkd.service.