How can I add this pluguin to ionic

[Provoo]

I follow the steps you show in the readme file and I got this error:

gdesign@veronica ~/d/i/c/hello [1]> cordova plugin add ../cordova-plugin-client-certificate
CordovaError: Could not determine package name from output:
up to date, audited 3 packages in 1s

found 0 vulnerabilities
    at getTargetPackageSpecFromNpmInstallOutput (/usr/local/lib/node_modules/cordova/node_modules/cordova-fetch/index.js:104:11)
    at processTicksAndRejections (internal/process/task_queues.js:93:5) {
  code: 0,
  context: undefined
}

Could you please let me know how to solve this error