JD Paypal Pro install problem

I have Joomla Donation installed and purchased the Paypal Pro plugin. I can't get it installed.
First I get

Your Extension appears to be written for an older version of Joomla!. You must enable the System - Legacy Plugin in the Plugin Manager if you wish to complete this task. So I turn it on. Really is this in supported in 1.5.20?

Second even if I turn on legacy mode it will not install.

* Plugin Install: No plugin file specified


What gives?


Thanks

Hi

This plugin is a Joom Donation plugin, so you cannot install it via Joomla plugins installation. To install it, please go to Joom Donation -> Payment Plugins, at the bottom of the page, will see a place where you can choose the plugin to install .

Thanks,

Tuan