All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad (ﷺ) is His slave and Messenger.
We ask Allah to grant you success and sound judgment, to suffice you with what He has made lawful, so that you have no need of that which He has made unlawful, to provide you with good and abundant provision, and to increase you in diligence.
As for your question, it is not sufficiently clear to allow for a proper answer; the method of trading in these companies is not clear to us, what exactly is being traded, or the nature of this trial account. All of these, and other relevant details, have a direct impact on the ruling and must be known before any answer can be given.
Thus, it is better for you to consult directly with a qualified scholar who has expertise and a clear understanding of such transactions, so that he may ask you about the necessary details and then provide an answer without relying on assumptions.
Allah Knows best.