Trying to install Owncloud client on Linux Mint Rosa Fails

I'm running a brand new Linux Mint Rosa (17.3 Cinnamont 64-bit), and I'm having way too many problems to install the owncloud client on it:

Given that the package on the mint repo seems to be outdated, I followed the owncloud page instructions:

sudo sh -c "echo 'deb http://download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_16.04/ /' >> /etc/apt/sources.list.d/owncloud-client.list"
sudo apt-get update
sudo apt-get install owncloud-client

Adding the repository key:

wget http://download.opensuse.org/repositories/isv:ownCloud:desktop/Ubuntu_16.04/Release.key
sudo apt-key add - < Release.key  

Maybe I did something wrong, because this is what happens when trying to install the client:

sudo apt-get install owncloud-client
[sudo] password for lalala: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 owncloud-client : Depends: libowncloudsync0 (= 2.2.0-2) but it is not going to be installed
                   Depends: libstdc++6 (>= 5.2) but 4.8.4-2ubuntu1~14.04.3 is to be installed
                   Depends: owncloud-client-l10n but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Going around the net, I found sudo apt-get install -f:

sudo apt-get install -f
Reading package lists... Done
Building dependency tree       
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

And trying to move further with the unmet dependencies led me to this:

sudo apt-get install libowncloudsync0
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libowncloudsync0 : Depends: libstdc++6 (>= 5.2) but 4.8.4-2ubuntu1~14.04.3 is to be installed
E: Unable to correct problems, you have held broken packages.

And this:

sudo apt-get install libstdc++6
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libstdc++6 is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded

Trying to remove potentially bad installed packages, leads me to this:

sudo apt-get remove libstdc++6
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libgbm1 : Depends: libgl1-mesa-dri
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

Obviously, trying to remove owncloud-client leads me to this:

sudo apt-get remove owncloud-client
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package 'owncloud-client' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

So... I have no clue where to go from here. Downloading and double-clicking on the .deb package installer leads me to the same error, and I've tried some apt-get commands more to no avail. Any idea?

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