1.Do I have to go to register an API?

It is not required, you can also leave it blank, our API is used by default, and the file is uploaded to our account.If you fill out your API, the file will be uploaded to your nft.storage account.

2.How to get the API?

Register a user on https://nft.storage ,generate a new free API key

3.Deploy on polygon failed?

Maybe your gas fee not enough,change to aggressive.

4.I have created a new NFT Collection,but i can't jump to "Easy NFT Bulk Uploader" page?

refresh the website after 1-2 minutes.

4.Do i have to choose the aggresive gas fee?

on the polygon network,yes. but no need choose aggresive on other blockchain.