Question about Seagate BarraCuda

I bought this HDD 2.5'' 4TB as 2nd disk for my HP Elitdesk 800 G6 Tower. Now I can't find a connection rail / screws / cage / matching adapter. HP seems not to drive the standard here (SATA cable I have, power connection is available). Does anyone know which parts I need to order and the exact designation? I have three HD bays 3x 3.5 and 1x 2.5 inch, would like to mount it in the 2.5'' bay if possible. FYI: I can't just attach the hard drive to the case with screws. It needs some additional parts. Thanks in advance for any assistance.