The first and usually only step is to download all your transaction data from Mandala and upload it into Koinly. There are a few ways you can do that:
If you want to use CSV files, you need to make sure to import your deposits/withdrawals and trades for ALL previous years - not just the current one!
That's it. The only other thing to be vary of is to tag your airdrops/forks so they show up as Income on your final crypto tax forms!