Is it permissible for a telecommunications company to stipulate the purchase of prepaid cards for one hundred million dinars to obtain an agency to sell them?

There is no religious impediment for the company to require the agent to purchase a specific quantity of its cards, as the default rule for conditions is permissibility and validity, unless they contradict the Book of Allah or the Sunnah of His Messenger (peace and blessings be upon him), and this condition does not contradict them.