Add ID or class to a Text Block?

I have recently joined on with Mediavine for ad placement on my site. They are having a hard time automatically placing in-content ads because I’m using the Avia builder. More specifically, they can do it, but the challenge is that the structure of my posts varies by post, so they can’t come with a uniform code insertion that’s guaranteed to target the correct areas on each post.

Their suggestion is that I add an ID or a specific class like “inner-content” to the single text block that my content is in, which would then allow them to target that ID or class for ad placement. However, I cannot figure out how to do that–I can add an ID to a color section, but not a text block.

Is there a way to add an ID or class to a text block?

Thanks so much for the help!