All you'd need to do on Discord is not allow people to create invite links to the server and keep the invite link fairly private by sharing it only to your members on your website.
On your IPS website, you can use user groups for customers or something like a club to create private forums where you can share the Discord invite link.
As for integrating the IPS website with Discord, I just started using MonitoRSS to import RSS feeds to Discord. https://monitorss.xyz