El Croquis on Digital Edition is too slow

I bought four digital edition version of El Croquis, and found that downloading them too slow. It is like each book will take up to 20 minutes to download.

After download, to view the book in digital edition is also super slow. It is like 20 times slower than reading a same pdf book on acrobat.

When I download the books, I can not read other books on Digital Edition, which makes me feels frustrating.

I do not know why the company Adobe could create a fast software like acrobat, but make the Digital Edition so slow.