Recently, one of my colleagues was trying to connect to PowerBI with his own mobile phone, but when he tried to connect to the application, he was receiving the following error:
“Could not authenticate because your corporate SSL certificate is untrusted by this device”
How the device it is not joined to the domain it was firing this error. So I know that the problem was in the certificates, so the solution was pretty simple.
We needed to connect to the adfs url, and install all the certificates in the device. Once all the certificates of the ADFS were installed in the device it was possible to connect to the service with an untrusted device.
Hope it helps!
Albandrod's Memory 