The moment a stable version of 64PTB1115 drops, we will update this guide with the fresh Bitly link.
This looks like a custom identifier:
The term "64ptb1115" appears to be a unique identifier that has been assigned to a specific piece of content. While we couldn't find any information on what this content specifically relates to, it's likely that it refers to a news article, blog post, or other online resource that discusses the latest developments in Android 64-bit. android 64 bits bitly 64ptb1115 new