Hello Tibor,
Thank you for your message.
In this scenario, you need to scan the QR-code via the 2FA app during the configuration process, i.e. on the Host settings configuration, you need to navigate to the 2-step verification tab in the Host Settings window and scan the QR-code, so this way the QR-code is added to your 2FA app.
After the Host is installed from the configured MSI installation package, your techs can access the QR-code in the Host settings -> 2-step verification tab -> Show Code - this way they can scan the QR-code, so it's added to their 2fa apps and they can authenticate from their Viewers.
Alternatively, you can also save the QR-code during the configuration process (e.g. by taking a screenshot of it) and then send it to your techs, so they can simply add the QR-code to their 2fa apps and logon to the remote Host from their Viewers.
Please note that in the case when the 2FA is enabled during the configuration process for a custom installation package, then the QR-code will be the same for all the Hosts that are installed using this installation package.
Hope that helps.