Trump was given four educational deferments, and then given a medical deferment (1-Y) for a minor medical condition, not an exemption. The military then abolished the category of deferment he was on, so his deferment was upgraded to an exemption (4-F). That was something that he (or more specifically his father) would have had no power to influence.

When the conscription lottery was introduced in 1969, Trump's birthdate put him in the 356 out of 366 category. The draft never came close to that number, so he wouldn't have been called up anyway. Again, something beyond his control.

I'm not saying there weren't shenanigans, but people overstate what Trump would have been able to achieve at the time. Biden, for example, received five educational deferments and and then an exemption for asthma. Again, not something he personally would have had much power to influence. The military have the power to reject anyone for any reason, as they should, and perhaps neither man was what they wanted at the time.