From the looks of it, the computer in question does not have Let's Encrypts root certificate, ISRG Root X1, installed in its system trust store. This root certificate is a requirement since late 2021. Normally, Windows computers install this certificate automatically from Microsoft Windows update servers. However, it appears that this mechanism did not work on this computer. While we do not know the cause of this, possible reasons are blocked update servers, firewalls, or disabled services on the affected machine.
Fixing this requires the user to figure out why the system cannot install the certificate automatically (this should still work, even though Windows 7 no longer receives security updates), or installing the root certificate manually.
The error message shows an expired certificate, because Windows tried to build a path up to DST Root CA X3, a different root certificate Let's Encrypt used until 2021. This root certificate has now expired, thus causing the above error message. Systems must now validate against ISRG Root X1.