PostgreSQL is fully supported, but you have to indicate the sequences for the tables when importing classes from existing database, like you said you did in the Export-Settings.
In the TMS Aurelius connection popup you can simply tell the importer to ignore the sequences, import the tables, and then add the sequences later in the mapping, if needed.
This was discussed in this topic:
Regarding UniDAC, design-time support is not installed by default because it's not a native Delphi component, so not available for everyone. You can install it manually, and it's also discussed here: