Hi,

If the module is not listing under the apps menu, it is not because of the module version issue. Is any other module in the same folder listed under the apps menu ? So, i would like to recommend you to cross check whether the custom addons path is set correctly or not.

Just open the odoo configuration file and check whether the folder extra_addons is added in the addons_path key.

If not see this video showing, how to set up new custom addons path in Odoo: How To Add Custom Modules And Custom Addons Path In Odoo

Regarding the v12 module, if you need it use it in v14, just set up the custom addons path correctly and once it is listed under the app menu, try installing it, some times it will get directly installed without any change, some times, the code need to be adjusted as per how it is coded. Better try to install and see, if you have any errors during installation, fix it one by and go ahead.

See: How To Migrate Odoo Modules To Another Version

Thanks