The Kobo devices should have no problem with Adobe Digital Editions (ADE) documents. I am not sure about Kindle devices, on stock software. I think the process is still that you Establish your Adobe account ID and install the ADE program on your PC then add your devices to your account. It used to be up to six devices, if I remember correctly.
Koreader is an addon reader that works on Kindle, Kobo, PocketBook, and Android. It is also able to read many different file formats, which could be an issue at such a site. Also, you may be able to
sync progress and highlights between the devices. ( I haven't used that feature, and it is relatively new.)
Download page.
Nightly build.
Stable release, in case the nightly can't handle your device.
Luck;
Ken