The first and usually the only step is to download all your transaction data from ExtStock and upload them into Koinly. There are a few ways you can do that:
Note that if you want to import CSV files, you need to make sure to import your deposits/withdrawals and trades for ALL years !
That's pretty much it. The only other thing to keep in mind is to tag your airdrops/forks so they show up as Income on your final crypto tax forms!