Copy the link on the 2FA installation link button in your Lemmy account settings and put in the secret=
value inside the Secret Key (required) field of 2FAS (heads up, it's going to be fairly long), and under additional info you need to change the Algorithm to SHA256
. Everything else stays the same.
Another way would be to use an addon (ex: on Firefox) to generate a QR code from your desktop browser by right-clicking the 2FA installation link and clicking QR code from link, then scan the QR code into 2FAS.
Always make sure you have a backup of your 2FAS data, either local or cloud-based.