You are trying to update a different devices firmware to a first gen single bay My Cloud. The second gen single bay My Cloud has different hardware. The first gen single bay My Cloud has been relegated to End of Updates status by WD.
WD Product Software Support Status
https://support-en.wd.com/app/answers/detail/a_id/28740
End of Updates - For product out of warranty and no longer manufactured in the last 4 years: end of software and technical support.
If one wants to try using an alternate OS on a single bay My Cloud, there are several discussions on various OS’s one can try and use.
Clean OS (Debian), OpenMediaVault and other “firmwares”
https://community.wd.com/t/clean-os-debian-openmediavault-and-other-firmwares/93714
