Hello. I'm very new to all of this. I read on AI platforms that i could buy the digital "heroes of the borderlands" and upload that adventure to DnD beyond "Maps" i can only find a couple pre made ones and no place to upload the adventure I bought. any help would be appreciated it. 

Heroes of the Borderlands is a digital product on D&D Beyond; you don't need to "upload" anything. It's already here: https://www.dndbeyond.com/sources/dnd/hotb

If you want to use it in Maps VTT, first create a new campaign: https://www.dndbeyond.com/campaigns/create

Then, once the campaign is created, go to Maps VTT and select the campaign you just created: https://www.dndbeyond.com/games

In the Maps Browser, scroll down to the "Adventures" section and you should find Heroes of the Borderlands right there.

Hopefully this will serve as a lesson about trusting "AI platforms" to be accurate about anything.