how do i install a plug-in jar files onto the cloud instance?...

You need to have one of the authorized technical support contacts for your organization create a case requesting the deployment of the plug-in in your Appian Cloud instance. Please also note that only some plug-ins are approved for deployment in the cloud.

If you're working on a trial instance of Appian Cloud, you can coordinate the deployment of the plug-in with your account executive or the sales engineer working with you during your trial period.

thank you.