Impossible to fulfill epub in android

Hello,

Yesterday I tried to subscribe to the digital service of a public library. I downloaded its MIUI app to read ebooks, while I had another working epub reader on my phone (pocketbook).

Suddenly, I could no more download ebooks  (using acsm links) using neither one not the other app. I only get generic "fulfillment" error, no explaination. Even Adobe Digital Editions won't work, giving no hint at all.

I checked my Adobe Id and found nothing wrong with it. I'm getting mad.

Could you please help me understand?

I'm using an android 7.0 smartphone.

Thank you