Hello, I have installed version 4.8 to test and check what's new :)
When setting up fixed costs for a DPD courier or whatever, the store does not physically see it. I have a cost of 0 when submitting.
I also added the cost by weight option for checking, but it does not matter when placing the order, the shipping cost is still in the cart 0 PLN
Is this a problem with the beta version? does anyone know anything about this?

Hello Marcin,

There may be a few reasons for that. First of all, please ensure that your customer role doesn't have the "Free shipping" checkbox marked. You can check it here:
https://yourstore.com/Admin/CustomerRole/List
Secondly, please ensure that your product doesn't have the "Free shipping" checkbox marked. You can do it directly on the product edition page, in the "Inventory" tab. Thirdly, on each customer, you are able to check "Free shipping to the next order".

Thank you :) indeed, the products had the free shipping option selected. The problem is solved :)