In a battle between mystical combatants with similar Authorities, the concept of Compatibility held no sway over who would come out victorious.
The only things that mattered were each Combatant's level of Authority and their corresponding Understanding of the domain they held Authority over.
Hence the reason Ana saw the battle ahead as a troublesome affair.
Perhaps, if Thera had stuck to just using her own Authority, Ana would have been able to suppress her, leaving the Mystic weak enough to be easily subdued.
Unfortunately, the Abyss Wheel Mystic had gone ahead to borrow the Authority of the Timeless Serpent which was easy considering her proximity to his location, ensuring that Ana would ultimately be on the losing end should they attempt to go into a battle of Wills.
It also didn't help that this was Ana's first time going against an opponent with the same Authority as her which meant she had no prior experience to draw upon.
