Why can't I transfer book from computer to e reader?

I am going to use this thread, because it asks the same question I have.

I recently got set up with e-library account and overdrive.

I run an Imac with OS 10.13.3

I downloaded adobe ADE 4.5.6

I successfully borrowed two ebooks, and transfered them to the Kobo device.

Once those were read, I deleted them in ADE, and returned them in overdrive.

Now, when trying to get the next ebook onto the Kobo, I get stuck trying to get it into ADE.

I borrowed the ebook, downloaded the copy to my downloads file. When trying to drag the .ascm file into ADE, nothing happens. If I go through the file menu to manually select it from the same folder, it is not selectable.

I am stumped, and haven't found any troubleshooting for this issue. Seem like this is overly complicated, and when a program fails at its sole purpose, I get frustrated....

Thanks for any help....

Matthew