I've found more data from the listing.

Name:  HW-532 Powr ratings.png
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This is meant to power motors; hence the use of the flyback diode we're supposed to add on the power connection, and the priority to isolate both sides.

I'm going to be powering LEDs, no mechanical devices. I don't really care about isolation, since both sides are getting power from the same source.

And that's how I answer my own question (I think).