What client?
Discussion
damus
Make sure you have the latest version then set this field in Edit Profile form. Needs to be an lnurl address for a wallet that works with zaps. I’m using WOS for now. 
So in Wallet of Satoshi take the Lightning Address (looks like an email) and copy that. Here’s where it is in WOS.

Then click on your profile in Damus and hit the edit button on the top right of the screen. You’ll be presented with a place for ‘Bitcoin Lightning Tips’. Copy that Lightning Address from WOS there. Mine looks like this.

After you enter that you’ll know it worked because there will be a lightning bolt button on your profile and zap icons on most users (people who’ve set this up for themselves). Let me know if you’ve got any issues further, I’ll help you out. 🤙