HAULIX music senders set download and streaming permissions on a per-promo basis. If you don't see a download button, then it's due to one of these scenarios:
1. You used up all of your allotted download attempts.
If this is the case, contact the respective publicist/label and request that they reset your downloads.
OR
2. The promo is streaming-only.
Some publicists choose not to offer downloads with their promos.
OR
3. The music sender blocked you from downloading.