Can I use standard audio license for podcast?

Interesting. The download may be free, and it may be royalty-free, but it still needs to be licensed as a separate process before you can legitimately use it. If you purchase a stock subscription, then yes, you can license it and use it. What's not so clear is what happens if you try to license a piece whilst using the free trial - you may have to try this to see what happens. If it's successful you'll end up with a license code, at which point you should be good to go. Thing to do is to try it and report back, then we'll all know!

There is a page about Adobe stock here. If you scroll down it you will get to the bit about licensing (which carefully avoids this issue). There's also a page about license terms here which points out that there are indeed different levels of licensing - it's a bit of a minefield .