You are welcome. El Capitan doesn't require 64 bit applications. Apple is still working on that. If you have a mid 2010 MBP, you can upgrade to Sierra/High Sierra.
To check the model number hold down the option/alt key, go to the Apple menu and select System Information.
macOS 10.12/10.13 (Sierra/High Sierra) requires one of the following Macs:
MacBook Pro (Mid 2010 or later) Model 6.2 and higher
How to get macOS High Sierra
Sierra download
You can try to download it at the link below. If it won't let you, then your only options are to upgrade to Sierra/High Sierra/Mojave or find an older computer where you can download it using your Apple ID.
El Capitan
Check to make sure your applications are compatible. .
Application Compatibility
El Capitan 10.11 Compatibility information
macOS Sierra 10.12: Compatible Apps
Also check to make sure there is a compatible driver for your printer.
Do a backup before installing, preferable 2 backups on 2 different drives.