If you're making it for the first time, you needn't "E3_Spool_Holder_V2 quick release plate".

If you have this parts https://www.thingiverse.com/thing:4441076
You just need to print "E3_Spool_Holder_V2 hot shoes" and "E3_Spool_Holder_V2 quick release plate".

Apologies in advance if there is a similar thing uploaded\published that I have not noticed.

You will need 3 x M5 x 20 mm Bolts + Nuts to attach the stock Ender 3 spool holder to the thing. You will also need 2 - 4 M3 x 10 mm Bolts + T nuts to fix into the side 2020 extrusion.