Mac mini (Late 2014) Thunderbolt ports

That will not work for bus powered USB-C drives. You’re best bet for an external boot drive, is to just get and use a USB-A 3.0 SATA SSD. FWIW a 3.0 SATA SSD will give you around 500 MB/s which is around 7 or 8 times faster than your 2014 Mac Mini’s slow 5400rpm internal drive.

You can not connect that drive to your 2014 Mac Mini’s Thunderbolt port.

If it also came with a USB-C to USB-A cable the you will need to use that cable.

If not, them you will need to try a female USB-C to Male USB-A adapter.

for example > https://www.amazon.com/Crucial-USB-C-USB-Adapter-CTUSBCFUSBAMAD/dp/B08FSDMVNP/ref=pd_aw_fbt_img_sccl_1/144-3340786-9915212?

or > https://www.amazon.com/Satechi-Type-Type-C-Adapter-Converter/dp/B07KCL8WZK/ref=asc_df_B07KCL8WZK/?

The Thunderbolt2 port on your Mini does not support USB in any form, unlike the later USB-C Thunderbolt based Macs.