CoinTracker currently lacks native support for ADA staking rewards. In the meantime, by following the steps in this guide, you can capture your ADA staking rewards using a public ADA address (for example from Daedalus) and a third-party tool called PoolTool.
To get started you need to find your ADA address on pooltool.io. Click 'Rewards Data for Taxes', then paste your ADA address into the field:
Then you'll click the blue arrow to view the address details:
At the bottom of the page that loads, you'll find the Export Tool. You can use the default value for the format field, but change the currency to Cardano:
Download the CSV file for each of the years in which you received staking rewards. You can either upload each year as its own wallet, or you can combine these files into one CSV: using Google Sheets you could copy everything but the header (the first row with column labels) from the 2021 sheet and paste it at the end of the 2020 sheet, then select File > download as a CSV.
The final step is uploading this CSV to CoinTracker. Add a CSV wallet, in this example it is called 'ADA Staking Rewards' but any name will suffice. If you're uploading one file for each year you might call it "ADA rewards 2021", for example.
Click Import, and a few moment later you can check your wallets page. The import is successful, and we see our ADA Staking Rewards wallet in CoinTracker:
If you receive more rewards and need to update your transactions, simply follow the steps again to download your updated rewards CSV, remove the old wallet by pressing the small down arrow shown above and selecting 'Remove Wallet', and then upload the new CSV.