Regarding SSD:
Sandisk SSD Plus (120GB, 2.5") is compatible regarding:
Form Factor: 2.5"
Data storage interface: SATA III
SSD Protocol: AHCI (SATA)
For example, Blue 3D NAND 2TB was tested with these features as well
https://documents.westerndigital.com/content...

Storage capacity of the SSD
Perhaps it is better to choose an SSD with a larger storage capacity (256 or 512 GB), because Windows 10 Home plus other important software already take up about 50 GB of space at the beginning.

Which mainboard / motherboard is used? If both memories are compatible with the mainboard and the necessary interfaces are available, then: i. O. Save the operating system and certain reliable programmes such as Microsoft Office on SSD. Ordinary files, which are often only stored temporarily, should be saved on HDD.

WD Blue is compatible with mainboard
Mainboard:
https://dlcdnets.asus.com/pub...

WD Blue:
Tested: WD5000AZLX
So all of the WD Blue group with 3.5'' are compatible with the mainboard.
https://documents.westerndigital.com/content...
Aside:
Has the same interfaces and the same form factor (3.5'') as Red and Black
WD Red can also be used with desktop PCs (individually); is used because it is cool and quiet.
https://www.westerndigital.com/de-de...
https://documents.westerndigital.com/content...