where does it say follow the law?

Given the sheer fact of timing, this Administration recognizes that actions to implement the law simply must fall to the next Administration, which takes office on Monday.

also this

https://www.pbs.org/newshour/amp/show/biden-white-house-says-enforcement-of-tiktok-ban-will-fall-to-trump-2

So this is entirely symbolic?

Exactly. It is symbolic. It has no effect.

edit: tiktok's already in the process of restoring service despite the law technically being in place lol