You need to use the extension for the botclient to work

Chrome Web Store: https://chrome.google.com/webstore/detail/discord-bot-client/dighjoofcdkhjloaeakagmfnbiehebbb If you want easy installation you need to wait until Firefox approves the extension

Why: Discord changed their servers, that the browser can't just download the source code anymore.
Only extension have privileged permissions and can bypass the block.