Canon PIXMA MG6620 on Linux Ubuntu
Open a terminal
sudo apt-get update
sudo apt-get install cups libxml2 libglade2-0 libpng1* libtiff*

Download the driver.
I had to use the Canon India link, as the Canon USA link did not have the Linux drivers. I also had to use the MG6670 model instead of MG6620, as the MG6620 was not listed.
https://in.canon/en/support/PIXMA%20MG6670/model
I downloaded the following printer driver:
IJ Printer Driver Ver. 5.00 for Linux (debian Packagearchive)
This software is a printer driver for printing using the Canon IJ printer.
Last Updated: 09 Sep 2014
Size: 474 KB

Extract the file: cnijfilter2-5.00-1-deb.tar.gz
Go to the downloaded file directory and extract the file:
tar -xvzf cnijfilter2-5.00-1-deb.tar.gz
cd into the cnijfilter2-5.00-1-deb directory and execute the install.sh
sudo ./install.sh

After the driver install, I went to Printers and the MG6600LAN as listed.

I did a test print of a Web page and the printers listed were Canon_MG6600_series, MG6600LAN and PDF to print from. I tried the MG6600LAN and the printed page was not clear, as though the driver was missing. When I chose the Canon_MG6600_Series, the printed page was clear.

Worked well.

I also download the scanner driver:
ScanGear MP Ver. 3.00 for Linux (debian Packagearchive)

This is a scanner driver for your selected model.
Last Updated: 09 Sep 2014
Size: 236 KB

I followed basically the same procedure for installing the scanner driver. But, when I ran the installation, the installation errored out, stating the driver was already installed. So I do not know if the scanner driver is part of the printer driver or Ubuntu has a default driver that recognized the MG6620 scanner. I ran the scanner program, and the scanner program recognized the MG6620 as “Canon PIXMA MG600 Series.” I did a test scan and was successful. The ouput of the scan is PDF.

FYI: My installation was done with the printer being wireless. The test printing and scanning was all done via wireless as well.