The plugin itself has a folder that contain the charge flow and the Oauth to connect the vendor account to Stripe, however, feel you free to try, when you are going to connect the vendor account in test mode, there’s no test mode for the vendor account creation.
So while actually is possible pay in test mode in order to see if everything works, it seems that you can’t use fake Stripe account for a vendor, so you should type in a registered account.
On WCMP instead, such test mode is there also in order to create the vendor account, you just click on a link to switch the step and Stripe automatically create the account and connect it to your dashboard.
Also, be aware that if WCMP has used the same charge flow used for its own multi vendor plugin, you will responsible for chargeback, refunds, disputes and you will always need a certain amount of money in your balance in order to pay vendors, as Stripe will pick this money from there, and not from the incoming money of your customers.