so to get the linux drivers for Epson, one starts here http://download.ebz.epson.net/dsc/search/01/search/?OSC=LX
and entering xp-620 takes you here http://download.ebz.epson.net/dsc/du/02/DriverDownloadInfo.do?LG2=EN&CN2=&DSCMI=55539&DSCCHK=5ef6ec128765534a989152269045f12fc58077f2
and for a 64bit ubuntu, epson would recommend the epson-inkjet-printer-escpr_1.6.13-1lsb3.2_amd64.deb
when you click to download, the dialogue box should offer to "OPEN" the package; accept that, as it means the installer will OPEN the package .. meaning install it .........
for any printer, there are 2 steps:
1) set up the drivers
2) register the printer: ie tell the system about your new machine
the above installs the driver; you might need to go to PRINTERS and select ADD so it adds the new machine;
converse is, ubuntu may do it all for you; but perhaps use a different driver; so if you end up with 2 icons for the printer, right-click on each; select PROPERTIES and look in MAKE & MODEL to see which is which .....