No, they just print some marketing features of the board there, it has nothing to do with the slots.
Your slots are called DIMM (Dual inline memory module) A1 and B1,
View attachment 194636
On such a two-slot board, the left slot is to be populated first. But it's good to try both slots, if you only have a single module anyway.
Now, as to the performance issue of using a single module, which i alluded to. Always use a kit of two modules on a platform with dual-channel RAM (which means, on all current desktop motherboards), unless this is meant purely as an office PC where performance is irrelevant. If you use a single RAM module and thus only single-channel, the RAM bandwidth is cut in half. So your DDR5-5200 effectively turns into the performance of DDR5-2600, compared to using two modules.
So you see how this isn't the best solution to begin with. But of course, it should not cause the DRAM LED.
First of all, make sure you are waiting an ample amount of time for the initial memory training to complete, at least two minutes or so (but i take it that you have waited for quite some time already). Secondly, it can take a surprisingly large amount of force to properly insert a DDR5 module into the slot, see
here,
here, and
here. So make sure the module is really pressed well into the slot and the plastic latches on both sides have engaged. Note that you cannot put a DDR4 module into a DDR5 board and vice versa, because the notch placement is different:
What you can do, check the CPU socket for bent pins. For that you would take off the CPU cooler, take out the CPU, and check for bent pins inside the CPU socket, which can easily happen from some mistake during CPU installation. Also see
here and the following posts. While they are technically all bent, the pins all have to look completely uniform under light, the tips of the pins have to line up in a perfect pattern, with none visually sticking out from the rest. So if you have some pins that don't look like the others, then you really have some bent pins. Ideally take some photos of the socket, upload to an image hoster and link them here, even if you don't think there are bent pins (sometimes they are not that easy to spot for the untrained eye).
Lastly, i'm curious, what's your PSU and your CPU cooler?