To begin with, you'll need to invite the bot to your server using the link below. Make sure to give it the Administrator permission when doing so!
In order to use the bot properly and make it function correctly, you need to make sur it has the Administrator permission and is above every role as shown in the gif below. If there are some roles you don't want to delete, just keep them above the bot and it won't be able to remove them.
If the bot doesn't have enough permissions, it will send you a direct message. Unfortunately, if your privacy settings don't allow the bot to DM you, you won't get any error message.