Dear @Harlerunner thank you so much for your post and for giving to Athletica WR a try!
Can you please let us know whether you are using Android or iOS please?
A while ago a trick was needed to make the oauth-link work on androids. Not sure it’s still the case.
Can you please have a look at this? 
I understand it’s something bothering Android users. Hopefully we’ll get to fix this as soon as we have the chance.