The CSR generator needs to support SAN's as it does in the SMA v8.1
I am speaking from SDA v5.1 perspective. I do not know if SDA v6.0 has already resolved this. The SMA v8.1 resolves this issue.
The issue is described in this knowledge base article:
The SSL certificate signing request feature needs to support the entry of SAN's.
This is still an issue with the SDA (K2000) at the current version (9.0.146).
This first request was made in 2018, almost 5 years and there doesn't appear to be any progress.
Steven New commented
Still needed for the K2000