From looking at the RME site, the cable supplied gives you the two midi in/out ports presented using 5 pin din connectors. The ADAT connections are referred to as Optical connections, so you need optical cables of the correct type to link to the ADAT to analog converters.
The RME converter compatible with your card would probably be this one
http://www.rme-audio.de/en/products/m32da.php in either the 32 or 16 channel version. The website says
The M-32 DA's four ADAT inputs provide simple connectivity with other studio equipment. A combination with RME's HDSPe RayDAT makes a perfect partnership, realizing the transfer of 32 channels from a Mac or PC with regular optical Toslink cables at an unbeatable price.
Sometime ago I looked into using interfaces which used ADAT outputs and ADAT to analog converters and thought it rather complex, and I was concerned that the quality of the RME solution might be compromised by using lower quality ADAT to analog converters from other manufacturers. I also seem to remember that there was a potential problem with sample rate switching with some combinations of computer interfaces and some ADAT converters.
I’m interested in what made you choose this solution.
Iain