Insert HDD and SSD

Hi,

I've got a new Dell Precision 3561 and wanted to insert two disks into it. However, I faced some problems:

1) The specs says: "One SATA slot for 7mm HDD 500 GB/1 TB/2 TB" I tried to insert a 1 TB HDD (Western Digital WD BlueTM 2.5-inch HDD, wd10spzx-21z10t0). However, I don't see the common possibility to connect the HDD, the connector is on the side of the slot. Do I need a sort of adapter here? Also, can I use SAMSUNG 850 EVO SSD in this slot?

HDD slot (left bottom corner)

2) Specs: Two M.2 2280 slots for solid-state drive 256 GB/512 GB/1
TB/2 TB

I inserted a SAMSUNG 860 EVO which indeed could fit the slot. However, either in boot menu nor in Windows the SSD is not recognized. Note: the SSD is not clean: It contains Ubuntu, GRUB and NTFS partitions.

What do these texts mean: "This SSD requires termal plate" and "no hybryd Optane/SATA?

Thank you for your help!

SSD_2