To work with files API, you need to obtain your drive name.
To do so, you need to pass drive_url to with parameter while getting account information.
As a response you will get your drive among other information about your account.
{
"drive_url": "https://drive-c.kommo.com",
"_links": {
"self": {
"href": "https://accountname.kommo.com/api/v4/account"
}
}
}
In this case it is drive-c and your base URL will look like https://drive-c.kommo.com/v1.0/files.