me too
the same error
pi4
Linux raspbx 5.4.72-v8+ #1356 SMP PREEMPT Thu Oct 22 13:58:52 BST 2020 aarch64 GNU/Linux
can not install zerotier-one_1.6.1_arm64.deb
only [zerotier-one_1.6.1_armhf.deb] (https://download.zerotier.com/RELEASES/1.6.1/dist/debian/buster/zerotier-one_1.6.1_armhf.deb)