The is typically hosted on private user portals provided by the hardware vendor (such as DeepSpar or DFL official sites). If you are an authorized user, log in to your account. If you are looking for the software independently, be cautious of "cracked" versions, which are frequently infected with malware that targets storage controllers.
DFL does not host their software on public repositories like GitHub. You must obtain the software from verified sources: dfl-srp download