Go to https://legacy.swarm.city and select "Enter here".
With the first visit to the Terminal everyone must start by creating a new Swarm City user account. When creating a new user it is stored locally on the device.
If you previously created an AC wallet. You will be able to load your AC wallet and create a new vault for your tokens in the Terminal. If you have no tokens to convert then you can simply create a new wallet by creating a password and backup.
If you have ARC tokens then you will have a few options to access your tokens and you will be prompted to exchange ARC to SWT as long as there is an ARC balance in your wallet.