Use SOAP API
Ok, so the thing is, the instruction is missleading.
First, we should save the URI from the login response.
Than later it says: " The endpoint URI looks something like this: https://MyDomainName.trailblaze.develop.my.salesforce.com/services/Soap/c/36.0."
As I was trying to use what I got during the login, and using this format of my URI:
https://mindful-unicorn-81efjx-deved.trailblaze.my.salesforce.com/services/Soap/c/59.0, I got errors all the time.
Then I was super annoied, and simply copied my URL from the browser, and added the "/services/Soap/c/59.0" part to the end. It looked like this:
https://mindful-unicorn-81efjx-dev-ed.trailblaze.lightning.force.com/services/Soap/c/59.0
問題は、その指示が誤解を招くということです。
まず、ログイン応答から URI を保存する必要があります。