Hello @tcoulon ,
You may first try the troubleshooting described at Get /e/ OS - e Foundation - deGoogled unGoogled smartphone operating systems and online services - your data is your data and log in again afterwards.
If you still have problems with the installation of paid apps, you may try Aurora Store, see [HOWTO] Download every app in the Google Play Store thanks to Aurora Store. (The article states at the beginning that it is outdated because App Lounge allows for the installation of every app - this is usually correct, but Aurora Store is a good workaround if there are problems.)