The first part you have done correctly - externalized the where clause.
In the second part you are externalizing the enablement of the snapshot - you are not, here, externalizing the previous setting at another level, but the enablement of the snapshot in the job. You don't need to do this, and it also does not in any way act as an 'id'.
You do not need to externalize the snapshot enablement, assuming you always want to the snapshot to run.
Your externalization of the WHERE clause is fine though might be better to externalize this as 'where' rather than run_id.
Your syntax of the REST call also looks wrong.
You should untick the externalization of the snapshot itself, then use something like this to run the job:
Got it working! Thanks for the explanation.