My 2017 macbook pro's storage is ony 128G and I am planning to buy an external SSD drive:
Must I buy the cable? I am also attaching a picture of the adapter I am using for my macbook pro.

Samsung 860 EVO 500GB SATA 2.5" Internal SSD (MZ-76E500/AM) .
On the website it also recommends theCable Matters 3-Pack 90 Degree Right Angle SATA III 6.0 Gbps SATA Cable (SATA 3 Cable) Black - 18 Inches.
Link for the CableMust I buy the cable? I am also attaching a picture of the adapter I am using for my macbook pro.

As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.