I would like to use this plugin but…. please help

I need a zoom plugin and this is one of the few free ones, there aren’t even that many premium ones. I like the demo of this plugin, though at least one of the images in the demo didn’t work, at least one did, so it must work if it’s set up right. The problem is how to set it up right. I tried to follow the instructions in the pdf manual, but as I was following the instructions to delete the cache before specifying a new cache directory, I clicked the delete cache button and a warning popped up that it would be very hard for the server to rebuild the cache. It made me nervous so I didn’t delete the cache, thus not finishing the installation.

What’s the deal? Is it OK to delete the cache or not?

https://www.ads-software.com/plugins/wp-imagezoom/