The meaning of the wedding clothes part comes better from different translation:

And he saith unto him, Friend, how camest thou in hither not having a wedding garment? And he was speechless.
(Mat 22:12 KJVA)

The wedding carment means being washed clean (saved) but the "Friend" this parable did not did not believe or did not understand gospel to begin with, and thefore did not rejoice and had not the wedding garment on.


I hope this explanation makes sense?

God bless.