Hello everyone

I need help, I am in the process of learning and there are many doubts along the way. I have the following need from time to time. I deployed two contracts, one for an ERC20 token with the openZeppelin 3.0 library version, I also deployed a contract for the sale of these tokens with the 2.5 library version

In theory I don't see anything wrong, but when buying token, it just doesn't work. It generates an error and I don't know what the reason is. The address of the already verified sales contract is as follows.