We will be using the BIP-85 feature in the Coldcard to create the wallet we wish to use in Wasabi for their CoinJoin protocol.
Steps:
Select 'Advanced'
Select 'Derive Entropy' and read the displayed message. Press OK to continue.
Select the 12 word backup format.
Enter an index number. This can be any number between 0 and 9999. Write down this index number in case you need to recover this seed in the future. Press OK when you're done.
The derived seed value and other information will appear on the screen. Scroll down to see the available options.
Press 2 to use the derived seed
In the Coldcard main menu, select Passphrase.
Enter a passphrase (see here for steps).
Open the Wasabi Wallet app.
In the 'Wallet Manager', select 'Recover Wallet'.
Enter the 12 words obtained from your Coldcard.
Enter your passphrase in the password box.
Click on 'Recover'.
Double-click on the wallet in the right-hand menu to open it.
You now have a wallet generated by your Coldcard to use with CoinJoin.