VST instruments usually will automatically sync with the host DAW tempo. If you're dealing with a .mid (MIDI) file, that you've loaded into a MIDI track in your DAW, this should also be in the same tempo of your DAW.
Now, if you're talking about sampled audio loops that are loaded into a VSTi sampler, that's a different story. With audio loops (samples) the tempo is locked with the audio recording. Here are some ways to have audio loops match the tempo of the DAW.
Use .rex (or .rx2) files. These are ReCycled loops that are chopped up to turn each hit into its own sample. You load this into the sampler, load the related MIDI file, and off you go.
You can use Elastic audio/hitpoints feature in your DAW (Cubase) to stretch the loop to match the tempo.
Some samplers will be able to chop and/or stretch loops internally. NI Kontakt is what I use, but there are certainly others that are capable of doing this.