How can I get rid of the black background around of "glow" (transparency/.png) in Illustrator

[flx.bdt]

Hello Community,
Today I downloaded some .ai files from Adobe Stock to decorate my own private photo book i'm working on at the moment. Removing the background layer to save the files to .png worked fine so far. But then I needed some fireworks and downloaded a file that looked good to me, to do the same thing. But as I tried, a black background appeared behind the "glow" instead of a nice transparency (see in sceenshot).

Now my question is how I can get a nice transparent .png of the fireworks. Can anybody help?
Thanks a lot.

{Renamed by MOD}

[Srishti Bali]

Hi there,

Thanks for reaching out. Could you please share the stock ID of this file? 

Regards,

Srishti

[Monika Gause]

Hi Shristi,

those files are not wrong. They have been built in the way that is appropriate if it needs to be compatible with Illustrator version 10. But you cannot use them outside of Illustrator. And you cannot use them without a background.

[Monika Gause]

They ususally won't work without a background. You want to use them online?

Please see my video about how they work: https://youtu.be/Tiqm5hdQA5A

[manal shanableh]

those vectors are built to be used over black background.