Erling Haaland's agent Mino Raiola won't take him to Barca because they couldn't afford him and they are going backwards as a team , Real , City or Bayern are his only options. On the other hand, this agent is toying a lot of big clubs around. It’s time all big clubs to not buy players that choose him as agent. Then young upcoming players will reject him.
Honestly it is not about being in debt or not, teams like Barcelona could keep on making big debts and they could pay that later, that is how debt is used in football, they keep growing in debt but they keep growing in assets as well so banks can't just seize something from these teams, so they have to wait for the team to pay and teams know this and that is why they keep paying very old small amounts, make a brand new big one, and by the time they need to pay that big one, it becomes small due to inflation.
Haaland will not come purely based on how the team looks, even if Barcelona gets Haaland, they will not become a great team, hell I am not even sure they are better than Dortmund as of right now, maybe if Haaland switched sides then Barca would become better but right now Dortmund seems better team. I can't talk about Madrid but I can say Barca will be a very low chance.