Transfer ePub books from Mac to iPad

What an INCREDIBLY INEFFICENT way to organize ePubs. Itunes would automatically organize my whole library of hundreds of books, and they would all just show up so I could check mark the books I wanted on my iPad. It appears that now I have to copy each individual ePub to my iCloud drive, and then import each individual file from the files app on my iPad Air to Books. I have hundreds of books. I guess I can choose just a few, but MANY are reference books that I need to have on hand. Am I missing something? Is there an easier way to do this? I use Calibre to organize my ePubs, but I can't get it to talk to my iPad. It means that each book is in it's own folder. So I'm going to have to open every folder and dig out the ePub. Remember when we bought Apple computers even though they're much more expensive, because they made life easier. What the **** happened? Help?

The "best" way is the one that works for you. There are a few options:

If the ebook is purchased from Apple it will be available to download on all your devices.

If you want to synchronise from your computer to your iPad you will now use Finder, which has inherited this task from iTunes. As you note, iTunes been retired (except on Windows computers). See Sync books between your Mac and iPhone or iPad.

Or you could have an ebook in your iCloud Drive folder on your Mac and open an ePub file on your iPad using the Files app. See Access and manage your files in iCloud Drive

You can get further support on the Books app at Read books and more with Apple Books.

There is another way to sync I was unaware of earlier - I don't use the Books app and have only recently discovered how it can work with iCloud. It does, however, mean duplicating your Calibre collection because Books and Calibre can't service the same devices; Books requires iOS and Calibre non-Apple devices such as a Kindle - for which it works well I have to say.

However, if you go to your ePubs and import those you have selected into your Mac's Books app (ie. drag and drop) it will synchronise with iCloud and this then will send the ePubs to the Books app on your iPad.