I've tried to make royal icing and it did not work. I did clean all my equipment w/ vinegar and I just could not get anything to come together. It was really dry and I kept adding more water, just not a good experience. Any help please?

Cleaning with vinegar has been shown to be unnececessary. Egg white are more tolerant than that.

That said, royal recipes are typically eggwhite powder or meringue powder, water and powdered sugar. the recipe I remember is 5 tablespoons meringue powder, a scant 1/2 cup of water and 1 pound of powdered sugar. I generally sift the meringue powder.

What recipe did you use?

My recipe was:

3 tbsp meringue powder
4 c. powdered sugar (1 lb)
6 tbsp. water

SugarintheMorning that is the one i use and it turns out every time.

the equipment you are using is it plastic? Also how long are you mixing it for?

I used a stand mixer, no plastic, and I know I beat it for a long time and the consistency never changed. It was several mins, I believe 8-10. I really thought I followed all directions to the T.
Shouldn't it be like marshmallow? It was really dry and then pasty after I added more water.

yes, and yes. I just wash my bowl and paddle with really hot H20 and dish soap. Rinse it well and dry it well. let it cool from the hot water.

For the process i dbl the recipe in my kitchen aid, i think it works better.
Then i make xtra flowers out of the extra (if i have extra). Then i have them for a quick cake.