I am looking for a developer for a small WordPress plugin

Hi, my name is Thom, and I am the owner of a small business that specializes in change management training courses. I currently run a WordPress website, which I need some help with. I am looking for a developer for a small WordPress plugin. This plugin will be an addition to an existing WordPress plugin, called Mailster: [login to view URL] With Mailster, you can send newsletters and autoresponders to subscribers. These subscribers are categorized in different lists. I currently use Mailster to send digital downloads to people when they fill out a form. When the form is submitted, the subscriber is assigned to a list, which triggers the autoresponder. Currently, it's not possible to receive a digital download more than once. When a subscriber fills out a form a second time, he/she is already assigned to the list, so the autoresponder is not sent again. This is where the additional plugin comes in. I would like to have a plugin that clears these lists automatically using a cronjob, as shown in the image I attached. This way I can create dummy lists that trigger the autoresponder every time, because the list in being cleared after certain amount of time. I don't have a major budget for this. I am hoping to find someone that can do this fairly easily, but it's very well possible I'm underestimating the scope of the project. Please don't hesitate to respond with your price estimate.