I can totally understand the desire to have security on a website such as this. With so much PLR content, I have no doubt that's a treasure trove for nefarious people to try to download as much as they can as quick as they can. As a web developer, I fully understand the concept of security, including expiring cookies (i.e. automatically logged out after being idle for so long). However, what complete escapes me is the concept of requiring an end user to completely clear their cache to be able to continue downloading a file. Having to log back in after being idle is understandbale. But preventing a person from downloading whatever file they were attempting to download prior to the login page, to me, is just completely nonsensical.
From a security standpoint, there's a lot of things that can be done on the back end to not inconvience the end user. The first thing that comes to mind is the use of a CDN such as Cloudflare, which is free. The forums could be security in the same way as well as with various anti-spam plugins (e.g. Stop Forum Spam).