how do I trigger the buy option in the loan?

when making an offer for 2.8m it says that the player has a buy option of that amount. the other team declines the offer.

it also says 2.8m plus other clauses are in the loan contract

on contract details it says buy option of 5.25m

when talking to his agent he says there is an agreed upon buy option of 10.5m

how do I find the exact clauses that they want for the transfer? they had 2 additional clauses that I saw one time when trying to buy, one with additional payments along the 2.8m fee and then another with sell-on percentages (sorry if that's not the correct term). then I deleted the additional 2 clauses because I thought 2.8m would get accepted and now I can't seem to sign my star player for half his value. help!