Depending on your plan, we will sync all comments on all "live" ads within the 32 days prior to connecting an ad account, with the following limits:
last 300 active ads, every 4 hours if you have a Professional plan
last 2500 active ads, every hour if you have an Advanced or Custom plan
The limits for active ads are per profile. We sync last X active ads - it's not possible to choose which ads are going to be synced.
Once an ad has been synced, all comments made under it are synced on an hourly basis.