In most cases, sounds on BPM Create are available to download for 1 to 2 credits. Sounds that include a MIDI file are 3 credits. To see how many credits a particular sound is, simply hover your cursor over the sound and the credit requirement will display.
When you choose to download a sound, the credits will be automatically deducted from your credit total. You can always see how many credits are available in the top righthand corner of the platform screen.