I found the original ordering email. but I couldn't find the update.
Visit the following URL:
You will need to login with your Gumroad account, and then you'll see the books you have purchased from Gumroad; The Starling Handbook should be one of them. You can download the latest version from there.
Please let me know if you've got any troubles with that.
Why is the GPU memory so limited in air desktop?
Many people have been wondering that. 😉 Adobe probably simply wanted to make sure all platforms behave the same, and overdid that in this respect. 🙄