Geordie you're a diamond mate!!
Followed the link you provided, dl'd the Amazon Store app and dl'd Frontier simple as that. Have played the 1st couple stages just to test and other than being a lil slow on my phone it's all working so far
This topic has been open for about 2 weeks now and there's been not 1 bit of support from RL or Ubi in sight. It really wouldn't have been hard or time consuming for somebody to have came in here and explained what the issue was. Even a "You're old *** phone can't run it" would have sufficed ffs.