Can't speak for the parent commentator, but I gave zerotier a try and ended up dumping it mostly because it was unusably slow on single core Linux VMs, making it not a viable option for connecting lower tier cloud VM options. I believe this is on the list of things they're fixing with their next major version, but that version has been very slow in coming out.
i can't say about that specific thing but i've been using this daily 24x7 for the last 2 years now. it connects my 20+ pcs and laptops which are geographically apart but because of zerotier, they are in a local lan.
it does not have SSO, relying on the admin accepting/rejecting connected devices by a single checkbox.
this is in comparison to tailscale which uses Oath, meaning you have to create and maintain those accounts as well.
