I did send him a PM, but like you said he hasn't been on here for a while, since January. I couldn't be the only person trying to access the site though - does anyone know when it went down?
There's no much info about how else to contact them except through support on the website as they don't have any known social media presence.
According to
google web cache snapshot taken 16 Jun 2020 19:36:04 GMT the website seemed to be okay which means the website stopped working between 16th and Today. It could have even happened a few hours ago
Maybe let's wait and see if they can get back online soon.