The first and usually the only step is to download all your data from altilly and import them to Koinly.
There are a few ways you can do that:
If you decide to import CSV files, you need to make sure to import your deposits/withdrawals and trades for ALL years and not just the current one!
That's it. Don't forget to tag your airdrops/forks so they show up as Income on your final crypto tax forms!