I have downloaded bunch of plugins. Do I need a DAW to use those plugins or what?
If they are plugins, then Yes, you need a VST Host (DAW)
Since you are running windows, just do a search for DAW…
there are several free ones, (Cakewalk being one) and some moderately priced ones (Reaper being one). The choice of how to go is yours!!!
Some plugins also have a standalone application.
Kontakt, Komplete Kontrol, Reaktor, Guitar Rig among others can run without a DAW.
S3 StormBreakZ have standalone EXE. I can't use it because I need to register it to get working but it is a Legacy product. That is really infuriating to BUY software and then it is locked BECAUSE it is old.