I;m not able to install seafile-cli under ubuntu trusty on arm (qnap container)

[adamcharlie]

I'm trying to install the seafile-cli under qnap network attached storage within virtual box. The ubuntu version is trusty. I run add-apt-repository and the file in etc/apt/sources.list.d was created. After running apt-get update it looks like the new repository has not been taken into account. So I have copied the first line from (uncommented one):
"deb http://ppa.launchpad.net/seafile/seafile-client/ubuntu trusty mainrusty.list"
from sources.list.d to sources.list file. Now apt-get update displays the following error:
W: Failed to fetch http://ppa.launchpad.net/seafile/seafile-client/ubuntu/dists/trusty/InRelease Unable to find expected entry 'mainrusty.list/binary-armhf/Packages' in Release file (Wrong sources.list entry or malformed file). What am I missing?

[Adirelle]

It looks like this PPA contains binaries for amd64 and x86 only.