It has an spdif (optical) out, eARC (hdmi audio send) and a stereo line out via 3.5 mm jack.
So it the only analogue outs is has are stereo via the jack, you could connect that to dual RCA/phono on your receiver using a suitable conversion cable. If your receiver has an optical input you could use that as well although I have yet to get any 5.1 surround mode working myself doing this.
I have ended up using a hdmi audio extractor widget off amazon, which connects between my firestick and the TV) to get 5.1 (via optical) into my old Marantz receiver.