This overview page links the guides, to use this headscale server with the official Tailscale clients.
If there is no specific guide for your platform, you can try to install the official Tailscale client for your platform and configure it to use the following custom server (official Tailscale guide): https://users.nynex.de
By default, only traffic to other headscale devices and administratively configured routes will be sent over the VPN tunnel. In order to send all traffic over the VPN tunnel, select an "exit node" as a default gateway.