Can I update my Photoshop Elements 11 to the latest version, I'm using Mac

See here for the requirements, especially the OS version: Photoshop Elements system requirements

Mac OS

• 64-bit multicore Intel processor
• Mac OS X v10.11 through macOS v10.13
• 4GB of RAM
• 5GB of available hard-disk space to install applications; additional 2GB to download all optional content
• 1280x800 display resolution (at 100% scale factor)
• DVD-ROM drive (for installation from DVD)
• Internet connection required for product activation and content download*

Look here for buying your version: Version Comparison | Adobe Photoshop Elements 2018 vs 15, 14, 13

I'll move it over to the Ps Elements forum.

~Barb

Please post in the Photoshop Elements forum (this is the Photoshop forum): Photoshop Elements