This is a user forum. If you buy a disc version, in a box, from a retailer you get both Mac and PC versions. If you buy a download you only get one or the other. If you recently bought, you have (about?) 30 days to get a refund if you bought directly from Adobe.
You can try Adobe Customer Support, but version 2018 is probably too old for an exchange.
Good news or not, you might be getting new video editing software to go with your new computer. FWIW, Microsoft made me do the same thing when I bought a new computer last year.
Please take advantage of a free trial to ensure it does what you want before you buy the license.