I want to set up 2.1 system and I already have two monitors Focal Solo 6, but for better movie watching experience I need a sub. For now on I decided to get sub SVS PB-1000

The problem is is that I am completely noob when it comes to audio settings. The PB-1000 can accept RCA or Speaker level inputs. And I will need to get TRS to RCA adapters it looks like, but I am not sure.

So the main question is: can I set up pb-1000 sub via RME Fireface UCX? And if the answer is yes, would it be safe?  What do I need to know (maybe there are some special settings in TotalMix FX for that purpose?) and, perhaps, what additional equipment do I need (maybe some sort of wires?) to set these things up?

Additional details: I use OS Windows 10, 64 bit.

Any help will be much appreciated and thanks in advance.