licencing problem

‌I have the adobe digital editions for both my macbook and ipad. I use the app for reading ebooks from school. These ebooks are normally locked. My problem is that i cannot read the ebooks from my ipad even after syncing. I get this message when i try to open : E-LIC-ALREADY-FULFILLED-BY-ANOTHER-USER

so far i have deleted and redownloaded ADE, but i still get the same issue.