C7 Elements doesn’t support this directly. However, there are a number of third-party plug-ins that allow you to side-chain in limited-functionality hosts like this. Eg BeatRig Sidekick Extended — a compressor with another side-chain sender plug-in. It’s 45 Euros, but there’s a free demo. Alternatively, you could try a gain plug-in with MIDI learn — like Blue Cat Gain Suite (free). Then use a MIDI LFO (There are some freebies listed on KVR) to control the gain in time with the beat. Or, for $50, take a look at Xfer records LFO Tool, which would achieve a similar thing.