WF Tech Support here: if you just link to your mega account and we click on the URL, we will simply get redirected to the mega.nz homepage (or to our own accounts if we're logged in). Instead, you have to right-click on the folder your files are stored in and choose "Share link" - however, if you don't have such a folder you'll have to right-click on each file and copy its URL separately, so I suggest creating a folder and moving your books there, it will save you a lot of work. And I have no idea how that works on a mobile, you'll have to figure it out yourself.
If you should fail to provide a valid link soon, we may decide to delete the whole sorry mess of a thread for being such an eyesore in our neat and tidy Library.