Hello, I am unable to offer contract to players through detection. It says “insufficient funds” but I have 14M

The same goes for me

If you have made transfer offers and they are on hold, if you have made contract offers to other juniors, all this is taken into account when the next offers are made.
So, even if you actually have the funds, they are considered as 'blocked' (put in reserve) for the first offers.

Blagoje Vidinic: Si vous avez fait des propositions de transferts et qu'elles sont en attente, si vous avez fait des propositions de contrat à d'autres juniors, tout ceci est pris en compte lors des propositions suivantes.
Ainsi, même si vous avez effectivement les fonds, ils sont considérés comme "bloqués" (mis en réserve) pour les premières propositions.

It could also be a manager who's already offered a bigger contract, couldn't it?

No.