Follow the install and setup instructions for the SDA.
Do not encrypt/add a password. You're going to delete this after setting it up with Bitwarden.
Look in the
maFilessubdirectory where the SDA is installed. One of the files will be named
[your_steamID].maFile. Open it.
One of the JSON variables will look like:
You want your TOTP entry in Bitwarden to look like:
Get your SteamGuard recovery codes and store them in Bitwarden or somewhere else safe.
Clear info from and uninstall the SDA from Step 1.