The receiver for the Safari 2 isn't built in, but it's included with the kit - just plug it into the USB port, as per the instructions, video etc.
But that won't allow tail end sync, which seems to be what you want, the YN-622 is a tail end sync trigger and should work, just plug the transmitter into your camera hotshoe and the receiver into the Safari, which also has a standard 3.5mm jack socket. Set the Safari to something like half power, because at full power the flash duration may be too short, depending partly on your camera. However, on the standard Godox version of our Safari, which has longer flash durations, it seems to work OK at full power, except on some of the slower cameras.
I've tested the YN-622N and it works fine, but some people are reporting that the Canon version (YN-622C) doesn't work above normal shutter speeds, I don't know because I don't use Canon but there are now enough people saying this for me to question either the quality control or the design of the YN-622C. Last week, a customer had exactly the same problem, fortunately he also has Pocket Wizard triggers, so rather than faff around trying to get the Yongnuo ones to work, he is using his PW, which work perfectly with the Safari.