The AIO has to be set to clock from AES or digital in, in your case. It will transmit the clock automagically. But the external DA must be set to clock from the receiving clock.
There are very few cases where it would go right automagically.

If set incorrectly that can happen if both are set to slave, I have done that by accident and depending on the gear used, you will get silence or terrible noise. Silence means the device has proper safeguards.
So with one AD-DA one should be slave one master.
And to answer your question in advance, with many AD DA's there can only be one master. Depending on the setup this can be very logical or a gigantic puzzle.
I have a HDSP9652 with all digital connections used (All 3 adats and 1 spdif) so 8 devices and it was a puzzle ;-).
But once you get it it is all very logical.

Hi, there are several ways to achieve the objective.

I think it is the easiest and best solution from the handling point of view to make the recording interface the clock master, which is directly connected to the computer. Then the sample rate is being set by the DAW/application and the connected Clock Slaves can learn this clock from their digital input.

In the case of the ADI-2 DAC/Pro the clock signal is being refreshed and D/A conversion happens with its own internal FS clock.

If the devices, which you want to have as clock slave, do not offer a digital input port (ADAT, AES, MADI) - which is often the case for mic preamps - then you need to use WC (Word Clock).

In your case the AIO does not support WC, so you need to clock via ADAT/AES/SPDIF. It can even be the case that you need to make the external device to the clock source, if this device can not receive clock if there is no digital input. Or if WC is present, but your recording interface doesn't support WC like in your case.

Would be good to mention the product names, to see whats possible in terms of cabling / clocking.

So the preamp on the left works fully analog, no digital output ports ?

What is a  "Mytek Stereo 192 ADC" ? This here ? Mytek Stereo192 DSD DAC ?
Could you kindly name the products the way the vendor does ? Otherwise I am not sure, whether I found the correct one.
Even better would be to link with Thomman or the vendors product page.
Why ? Because then its easier for me to look at the back of the devices, which i/o ports it has, wc or not .. etc
In most cases this is the quickest way to get answers ...

As the AIO has no WC, use the ADC as clock master, all other devices clock slaves.

In this setup you could also think about whether to get a RayDAT which has a WC option.
Then the RayDAT could become clock master
- ADC clocked via WC
- DAC clocked by AES out.

In contrast to that a full RME solution could be a combination of
- UCX or UFXII/UFX+ and
- ADI-2 DAC or Pro FS R BE
Where the recording interface would be clock master and ADI-2 * clock slave.
By this you could set clock by the application/daw .. the ADI-2 devices perform d/a conversion with the internal FS clock.

Sorry my fault, when just looking to the product page on archive webserver
https://archiv.rme-audio.de/en/products/hdspe_aio.php
I had it wrong in my memory and though, that information about WC would be listed in the top right grey corner "connectivity".
It could be that you have maybe really a little advantage to use the clock of the device where A/D conversion takes place, it simply depends on, how good WC is implemented on that device.
To keep costs low and if you do not see any operational disadvantage, that you can also easily set the clock at the ADC.