You're facing a common challenge to smaller clubs in FM. You've got transfer funds but the board will not approve a higher wage structure. In my current saved game, my club has a balance of €1.2m, and I have nearly €400k in transfer funds, but I cannot offer more than €800 per week to a key player. That doesn't even match the wage that a lot of players are already getting at clubs of the same size and reputation. So there is no way to attract good players from the same division or higher. The only way to improve is to sign players on a free transfer and buy players from the nonleague ranks that will take a lower wage and yet are good enough to play.
After the first two seasons, the club was really at a point where it had to increase wages in order to take the next step, because we needed to get that next echelon of players, but the board refused. So I just did the best I could, and fortunately we've nearly taken that next anyway. Granted, if we win promotion, there is no way that we're going to compete at the next level without more to spend on wages, but it's still a long road to winning the promotion playoffs, which are murderous in the Spanish Segunda B.
We're also going to lose one of our strikers who has scored 50 goals in a bit less than three seasons, because we can't offer an acceptable wage. I was able to sign him to a contract extension previously, because I had cut down the wages and the board allowed me to temporarily offer him €2k per week. But immediately after, we were above our wage budget again and back to the old restrictions.