That is bad, humidity should never get that high. Get all the water out and remove the vent plug until the humidity is down. You should use the dry incubation method. Don't add water until day 18 when you remove the turner and get the humidity up to 55%-75%. Before that the ideal range is...
Starting around day 2, adding dirt from your chicken run can definitely be good and help your chicks gain resistance to parasites.
ACV in the water every few days is also good.
But do keep in mind that these things are just preventative measures, and if your chicks are sick you might need to...