Edit documents online in OwnCLoud

use only office, setup only office server and connect using only office app in owncloud.
After that you can start office works in webbrowser.

Let me know you want more info about this
http://www.onlyoffice.com/blog/2017/02/integrate-onlyoffice-online-editors-with-owncloud/

you can install and configure the "onlyoffice" by referring this URL
https://helpcenter.onlyoffice.com/it/server/linux/document/linux-installation.aspx

OnlyOffice is a biggie.  
CollaBora is another one
With more document management try Alfresco. (this is more like sharepoint, or a straight sharepoint drop in).

Both are based on LibreOffice as a server.

Then there are Etherpad and Ethercalc if you don't need large tools, but only work together in a text document or spreadsheet.

this is the  perfect way to install only office and integrate it.

Check this out.
https://www.linuxbabe.com/ubuntu/integrate-onlyoffice-owncloud-nextcloud

Hi Prabhin, I followed the instructions but got stuck here. Can you please help?

have you addded the repository, and which version of ubuntu you are using

Hi, we are using Ubuntu 14.04 x32 and YES, we added the repository:

tino@U2-OO:~$ cat /etc/apt/sources.list.d/onlyoffice.list
deb http://download.onlyoffice.com/repo/debian squeeze main

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tino@U2-OO:~$ uname -a
Linux U2-OO 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:12 UTC 2014 i686 i686 i686 GNU/Linux
tino@U2-OO:~$ cat /etc/os-release
NAME="Ubuntu"
VERSION="14.04.5 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.5 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"

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I upgraded to version 16 but it still did not help. The same problem occurred:
 

tino@U2-OO:~$ cat /etc/os-release
NAME="Ubuntu"
VERSION="16.04.5 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.5 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial

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after adding repo
do apt-get update and search for the package.

it should come.