I want to put my photoshop cs5 onto my new MacBook air. How do I do that without a disk drive?

Download & Install instructions https://forums.adobe.com/thread/2003339 may help

-includes a link to go to a page to download Adobe programs if you don't have a disc or drive

Also go to https://forums.adobe.com/community/creative_cloud/creative_cloud_faq

This information is a MUST DO to install old programs on Mac El Capitan

-you may not get the same error message, but these two links will help with old programs

Install CS5 on Mac 10.11 https://forums.adobe.com/thread/2003455 may help (also for other than CS5)

-also a TEMPORARY security change https://forums.adobe.com/thread/2039319

FAQ about Mac 10-11 https://forums.adobe.com/thread/1979303