Vaultwarden with Yubikey OTP

[amoorefilms]

Just set up a vaultwarden lxc using the script. How do I add Yubikey support? I get this error when I try and set it up.

[tteck]

Have you tried adding:

## Yubico (Yubikey) Settings
## Set your Client ID and Secret Key for Yubikey OTP
## You can generate it here: https://upgrade.yubico.com/getapikey/
## You can optionally specify a custom OTP server
YUBICO_CLIENT_ID=11111
YUBICO_SECRET_KEY=AAAAAAAAAAAAAAAAAAAAAAAA
# YUBICO_SERVER=http://yourdomain.com/wsapi/2.0/verify

to your .env file located at /opt/vaultwarden/.env?

https://github.com/dani-garcia/vaultwarden/blob/main/.env.template

[amoorefilms]

where exactly is the .env located? when I go to /opt there is no directory called vaultwarden

[tteck]

Which installation method did you use?
Alpine would be /etc/conf.d/vaultwarden
Debian would be /opt/vaultwarden/.env