I am an engineer and having my own business is one of my dreams. So, it is apparent that if I had enough money I would prefer to purchase a business.
this is good :) However, you need to introduce your prompt. In this case it deals with two options, the house or the business! So you need to talk about the other option too.
The manager's success is always dependent on their employee's knowledge, energy and skills .
Although I am aware of the importance of management in rolling a company or a business, but the most beneficial and prestigious one among all of the people, who collaborate in the project, is the "manager"
.... this sentence is confusing. Avoid writing long sentences that may get you carried away at the end. Although is a connector and you cannot have "although" and "but" together in one sentence.
You can write well.... Only you need to follow a more logical structure, which I suggested to you in a little while ago. Train yourself to put your writing in that structure. You can earn good marks by doing so. I'm talking through experience as a TOEFL taker :)
Good Luck!