Tailscale add-on: Unable to get to login screen

I have a fresh install of HASS 15.2 + Tailscale Add-on 0.25 on a Raspberry PI 4 and am unable to access the Tailscale login screen. No matter which browser I use on my Mac to access HA (Safari, Brave, Vivaldi (the latter two being based on Chromium) I get the the message “Failed to login” after going to the Web UI of the Add-on and click on “Log In”, thus I’m unable authenticate and to connect HA to my tailnet. Note that I am logged into Tailscale on my Mac when doing this. What am I missing?
Thank you!
Stefan

See here. Problem with login Tailscale on VM HASS OS - Configuration - Home Assistant Community