You can check the logs for detailed information about any errors that may occur, for example when linking to the Let's Encrypt account or requesting a new certificate. Logs relating to Let's Encrypt are available in both the System Message File and Audit LogFile. The audit log file contains logs relating to if the account was successfully registered or if a certificate is issued/renewed successfully. You can view both of these log files by going to System Configuration > Logging Options > System Log Files.