You got a unit which came with a printed manual
Last / online version here:
https://www.rme-audio.de/download/adi2profsr_d.pdf
https://www.rme-audio.de/download/adi2profsr_e.pdf
The free Adobe Acrobat Reader has a search function. So search for "ADAT" and very soon you will find this information on page 8: "Optical I/O (TOSLINK): The unit automatically detects SPDIF or ADAT input signals. The optical output can operate as ADAT or SPDIF output, depending on the current setting in the Settings dialog."
So its all there ... whatever the other device needs/supports.
The difference between ADAT and SPDIF is simply that its a different protocol which runs over the optical link:
ADAT supports
8 channels @44.1/48 kHz
4 channels @88.2/96 kHz
2 channels up to 192 kHZ
SPDIF supports always 2 channels @44.1 - 192 kHz.
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14