In case your promoter referred leads without using the referral link or signed up from a different device where the affiliate cookie wasn't set, you can add the leads manually for him. Normally, this should be an exception, it's recommended to encourage your promoters to use the referral link whenever is possible.
The lead should be in the trial/free period when you create the lead so when the purchase is made, the sale and rewards will be attributed correctly to the promoter. After the first payment, the lead will become a customer.
If you also want to add commission for the lead, click "Save lead then assign a sale".
To create a lead for a promoter:
go to Promotions section and search for that promoter(by name or email)
Once you find the promotion run by your promoter, click on the menu icon for that row(on last column).
Click on 'Add lead'
Fill the fields and click 'Save' or "Save lead then assign a sale"