Try this solution, but your IQ must be rooted.
If is not rooted follow the section "How to root" on this page:
https://wiki.mobileread.com/wiki/Pocketbook_IQ_701
Then install and use Root Explorer, go to user_data -> data -> data and delete com.overdrive.mobile.android.mediaconsole directory, try to reinstall the apk.
You can download Overdrive from here:
http://db.tt/xrYPbwb2