here's a post with instructions: https://www.palnet.io/palcoin/@isaria/the-palcoin-claimdrop-is-here

it's a bit confusing, but all you need to do is login to steem-engine.com (with your posting key or steem keychain), go to the "wallet" page and then click that tiny PALnet icon in the upper left of the screen.

Then you'll need to sign a custom JSON transaction with your active key via steemconnect (or have the keychain do it)... wait a minute and TA-DA...