Just ran into this issue today, my guess is that Stardock activation does not support proxy.pac file / proxy server.
Since I can't use the trial, I will find another product. Trials shouldn't require activation, and activation shouldn't be harder than using the product.
Our trial activations are industry standard; you supply an email address, interact with the email, and it's then activated - again, pretty straightforward.
That said, if your proxy is preventing you from reaching activate.api.stardock.net, you will indeed have issues, with the trial or activation. If possible, please edit your proxy to allow for this.
I have written a script that is not exactly for this, but it's included in this documentation (its commented out, the proxy stuff, but you will get the idea).:
https://support.stardock.com/space/SHC/2588835961/InTune+Deployments (the script is in the zips)
Sean Drohan
Stardock Product Lifecycle Manager