In September 2023 We purchased a complete kitchen appliance package and when trying to add each appliance individually I get the same error “incorrect password for [range] _e30A etc.
I have allowed smarttings location always. Restarted devices. Done install manually. Is there any easy fix? Again this happening to my range, refrig, microwave and dishwasher.
Welcome! I’m sure that’s very frustrating. 
Hopefully it will just turn out to be something simple like your phone isn’t using the same 2.4 GHz Wi-Fi that the devices are. 
That said, this forum was set up a number of years ago so that customers could help other customers with the smartthings home automation platform. It’s not officially monitored by Samsung employees, except for basic spam and harassment issues. And not that many people here have Samsung appliances. 
There is a separate “Samsung help community” for the big ticket items like appliances and smart televisions which is monitored by Samsung staff, and you might get a quicker answer there. Of course sometimes, they just send you back over here if they think it’s just an app issue, but it’s usually worth a try.