Can I use an adapter in this case?

[Julian A. Bustos]

[Matt R.]

Disclaimer: I am not a professional electrician.

The receptacle is a NEMA 6-20R, which should be 240 V, 20 A.

The plug is a NEMA 5-20P, which should be 120 V, 20 A.

So no, you can't use an adapter.  The outlet provides twice as much voltage as the appliance with that plug expects.