Hello,
I am not sure what you mean by P2P exchange.
This is a stand-alone, orderbook-based exchange, and it operates as described in the Exchange extension’s homepage: https://www.dashed-slug.net/bitcoin-altcoin-wallets-wordpress-plugin/exchange-extension/
Meaning that, for a trade to occur, there must be limit orders on the order book. When the orderbook is non-empty, users can place limit and market orders. (To clarify a common point of misunderstanding, there is no importing of liquidity or price information from other marketplaces.)
A detailed guide for how to set up some markets using this extension can be found here: https://www.dashed-slug.net/howto-setup-a-cryptocurrency-exchange-on-wordpress/
Please let me know if you have any specific questions on this.
with regards