Problem with Assimil language learning app

Hi,

before switching to /e/ I bought a method to learn japanese from Assimil, which is a well-known language learning method.

However, I can’t seem to install the method I payed for because the app needs some form of Google services to authentify me.

Is there any workaround to this ?

Thanks.

PS : I wanted to post this in the french-speaking community since Assimil is a french company and is mostly used in France. But, I’m unable to click the Create Topic button there. Anyone know why ?