I'm unsure on how to calculate my AMT for ISOs on which I exercised in 2018. However the company is not public, so I am not sure why I would be taxed on this yet?

You use the "ISO Exercise and Hold" interview to calculate the AMT adjustment for the shares acquired and not sold by the end of the year.  Just because you DO have an adjustment doesn't mean that your automatically going to be subject to the AMT.

I don't use any "online" version of TurboTax so I'm not sure if "Deluxe" has that capability or not.

The fact that the company is not publicly traded doesn't mean that the stock has no value.  The company is obligated to determine a fair value under Section 409A.

Tom Young