'Login was not sucessful:' Excited about FoxBrowser but can't log on to Firefox Sync either on Ipad2 or Iphone6!

[Loriliblue]

Hi,
Very excited to use your browser, however, I keep getting a 'Warning Login was not successful' error when using your browser to sign in to Firefox Sync.

Things I did so far to troubleshoot:
I double checked my FF sync account email/password (can login fine on three other devices with different browsers)
I changed my FF sync password (still can login on other three other devices with different browsers)
I deleted Foxbrowser app and reinstalled
I restarted Iphone and Ipad

Nothing is working... Any other ideas?

Background: I'm running
iphone6, iOS 10.3.2
ipad2, iOS 9.3.5

Please help! The ability to interact with my firefox bookmarks in a seemless way would be leaps and bounds more beneficial both at work/play and in the mobile/desktop environments! Thanks so much,
Loriliblue