Add a Mist Site
If not already done, please create a Site with Mist as the WiFi router. Please see
this article is on how to create a site.
Get the Portal URL from Spotipo
Navigate to Settings -> Mist on your Mist site and copy the URL from Spotipo.
Update Mist WLAN with Spotipo Portal
Login to your Mist dashboard and navigate to Site -> WLANs. Here select the WLAN you like enable hotspot or add a new one.
Under the Guest Portal section
Choose Forward to the external portal
app.spotipo.comunder allowed hostnames
Remember to un-select "Bypass guest/external portal in case of exception"
Save the configuration and Mist will generate an API secret automatically.
Now open the configuration again by clicking on the WLAN and copy the API secret.
Go back to the Spotipo dashboard and update this API secret
Voila!! Now wait for few minutes and connect to the network you just created, it should send you to the landing page.