As far as I know you need to authenticate through them.

Alternatively, you could setup your own vpn to do all this, but it is much more work and will likely have some cost.

When you connect to Tailscale, via cli it should give you a link to use to connect it to your account. You can get the ip address in various ways. One of which is just looking on your Tailscale dashboard. You need to have Tailscale installed on every machine you want to talk with.

I was going to say Tailscale. You will need to give more details about what didn’t work with Tailscale, but it has been pretty seamless for me.