Getting an obscure accessibility app

Hello all,

I tried to get the apk of DysCalculator from pretty much everywhere, but it just doesn't exist (or I couldn't find it). As a dyscalculic person, I need this app for my daily work and would greatly appreciate any help in getting the apk. The price in my local currency is just way too high and I also use a de googled phone.

The web version is free, but the native app for android is paid